When making small adjustments to speed in a paceline is it better to drag the front brake or the rear brake. I'm talking very small adjustments for the accordion effect. I understand soft pedaling and all but I still had a hard time matching speed when near the back of the paceline. I just seemed to notice if I used the rear brake they would often say slowing even though we really weren't.

You really want to avoid using either. In addition to soft pedaling, you can set up to take some more air for a subtle speed adjustment. And better anticipation will reduce the need to use the brakes to adjust speed.

That said, you can use a little front brake, while still pedaling to slightly adjust speed. If you're smooth, it will be subtle, the person behind you won't even know it, and you won't get the accordian going.

Light touch on the back brake will typically cause the rider to behind to brake even more getting the accordian effect.

My advice for beginners is to allow more space between you and the rider in front, then use that space to adjust your speed without braking. 6 inches is too close for beginners. You still get some draft effect with a full bike length of space.

I race and I barely get too close to the people up front. I leave about a foot or two on flats and about 8 inches to the side, about 3-4 feet if going downhill and very close 6in-1ft if going up hill. Be careful with people who throw the bike backwards when going uphill. If I want to shave speed I just move about a foot out of the line to the left side and open my knees to trap some air. It usually does the job.

I've seen WAY too many crashes. I wrecked hard once then I learnt my lesson, better work a bit harder than break your bones and your bike. Now every time I see a crash I am able to ride on the grass and keep going. It's been 4 crashes that I've avoided in the past 3 months.

Yes that is what I was noticing. We were drafting at about 12 inches but there were some other newer people in front of me and the smoothness of the paceline was not very good. It was a practice ride however and we learned a lot. If the person in front of you is too uneasy to ride as close as needed is it appropriate to ask to pass them or do you just grin and bear it?

If folks around you are yelling "slowing" when you touch your brakes, you are being heavy handed. Practice keeping a constant distance all the time, and anticipating changes in speed of the group. Also, sounds like your group shouldn't be riding too close together. Its best to ride with experienced riders, or at least folks you are familiar with when learning to follow a wheel. The lightly squeeze the brakes while pedaling thing is a good beginner/intermediate technique. You'll get better with saddle time, also be off to one side just a tad, in case you find yourself too close. rubbing wheels is an advanced skill...

That along with bumping shoulders. I would absoloutely advise against those as a beginner. Try to practice these things in a group that you are comfortable hanging on to. It is very hard to concentrate when 99.9% of your brain is just telling you to hold on to the group for dear life and you are exhausted.

Tired guys in over their heads often end up with broken collar bones or fractured wrists (and blame everything but themselves).
Learning to relax at speed is often an overlooked skill.

I'm in the learning process myself and as you say relaxing is quite critical... I used to unconsciously tense up over rough patches, etc.. but when making a conscious effort to remain loose and just roll with the jarring it feels better, is less tedious, you hold speed.. You need to be all rubbery...

Avoid the brakes unless absolutely necessary. As mentioned upthread, you can drift a bit to the side and catch a little wind to moderate your speed, but the main thing is to be looking up the road and anticipate any movements from 5, 10, 15 riders in front. What I was taught when first started riding in groups is to look at the jersey pockets of the rider in front of you and from there scan up the road. You should also be tuned into sounds of freewheeling rather than pedaling. That will often be your first sign.

Don't stare at the other guy's wheel.

The further back in the paceline, the more pronounced the accordion effect. Some riders are good at trying to give some space to reduce the surges, but others have no clue and make it worse. Riding near the front is usually much better, especially if the full group isn't rotating and some are cutting back into the middle of the line. I agree with caloso - avoid using your brake and if enough space, drift from behind the riders in front of you to catch some wind to slow you down. If you can't do that, just lightly feather your brake and give some more distance so you can maintain a steady pace. Watch and listen a few riders ahead of you so you can anticipate some slowing if/when it occurs.

What if you're a bigger guy, in the middle of the paceline, you're going downhill and you can't help but accelerate?

Last group-ride I was riding with relative twigs. I'm 200, the folks I was with on average were 130-160, guys & gals...If I wasn't up front pulling on descents I was having to do quite a bit to moderate my speed just to not overtake the line.

Hop on the front and pull everyone if safe?

The rules, with the group (leader...) I've been introduced to paceline riding with, are pretty tight...when to rotate off, how long to pull for, etc..

I'm getting the impression that not all pacelines operate that strictly...would I be correct?

Nope, some pacelines are more race-like. In racing, unless there is a chase or teams, it's pretty much a pack riding together. Everybody passes everywhere and the group effect is more like a pack instead of a line.

Sure if it's a training ride. Probably not if it's a no-drop group ride

Got it... Except I don't think it's considered good manners to move up the pace line to the front in a descent if I'm naturally out-accelerating it...?

the question my read better as: "how quickly can i safely reduce speed in a paceline?".

how one does it is immaterial, but if one employs coasting, it will provide an aural cue to those in front and an additional visual cue to those behind.

I'm a complete newbie to riding in groups. I have trouble NOT staring at the rear wheel ahead of me. When I try to focus ahead, I start to have trouble maintaining a smooth speed/pace and end up looking at the wheel ahead of me in an effort to avoid bumping into the guy in front of me. Trouble is, maybe because I'm short but, I can't really see past the rider in front of me without staggering, and I don't wanna go there either. In my case, where should my eyes be focused?

Just as the climbing pace may vary, same with the descent as you've noticed. Give plenty of space to roll through the descent without braking and merge back into the paceline when your pace matches theirs. This isn't bad manners, its just natural for the bigger guys to descend faster. If your group has a problem with this, then you'll need to brake to slow to the other's pace. Same with climbing. It's not rude to go around someone who's struggling on a climb, but you should attempt to keep the group together and not force the poor climbers to overexert just to keep up.

Even if you can't see past the rider in front, I still recommend looking at the jersey pockets rather than the wheel. The jersey pockets sit above the hips, and the hips steer the bike. Plus, staring at the wheel can have a hypnotizing effect, particularly when you are tired.

Here are all the things I try to do before touching my brakes in a pace line if I need to scrub off a tiny bit of speed, in priority order:

1. Soft pedal
2. Raise my body up and move my elbows and knees out to catch more wind
3. Offset my wheel to the left and soft pedal/coast which lets me catch more wind from #2 and gives me an escape if I start to overlap wheels
4. Very light dab on front brake if 1-2-3 fail to slow me down enough

If after #4 I'm still going too fast, I move left about a foot SMOOTHLY to get back down to the correct speed. HOPEFULLY the guy behind me isn't overlapping wheels at this exact moment since I have already moved out of line a bit in #3 .

This. Look straight ahead into the back/lower back of the guy in front of you and you will steer yourself without thinking too much about it. Gradually work your way into getting closer and closer as you get better.

Past the hips of the rider in front of you; rear wheel in your peripheral vision.