You should divide your "pack riding skills" and "bike handling skills" into two parts.
1. Riding in a pack.
2. Understanding cornering and braking.
Pack
I'm a huge fan of slow speed drills. Bumping (side to side, possible on pavement) and touching wheels (front-back, must do on grass/dirt and expect to fall repeatedly so keep speeds at "I can run out this fall" or "it's okay if I land and stick to the grass" so like 8-12 mph). These are drills where you need a willing partner. You can't work on this solo. Well, maybe a little bit if you're on rollers and you shoulder or hip-check the wall, but that's about it.
I've had first year racers diligently do the Bethel Spring Series clinics then come back to me 2 months later saying how helpful those drills were in a recent (like earlier that day) race situation. I got to one race and heard one Bethel pupil, an M50+ Cat 5, lost a slew of spokes out of his Zipp 404 front wheel. I was thinking to myself, "Oh, man, he definitely hit the deck, you can't lose more than a spoke or two in a 404 before the wheel is unrideable. Heck, if I started losing spokes I'd be on the ground." I was imagining a broken, crumbled man, distraught wife wondering why he's doing this bike racing thing, etc.
Then I turn and it's the guy. I looked at him a bit suspiciously for bandages and stuff. None. He never hit the deck. He lost more than one or two spokes, exact count escapes me but it might have been 6 or 7 spokes so almost half the spokes in the wheel. He hung on, maintained balance, and put his foot down at the end of it all. He said the whole time he was recalling all the stuff I'd said at the clinic about drops, hanging on, etc. He reminds me of that every now and then when I see him at the races.
I say that in 3-4 hours of dedicated bike drills you'll be a more competent close quarters bike handler than 50% of a Cat 3 field around here and definitely one of the best pack handlers in a Cat 4 field. 3-4 hours means 4-5 times where you do a 45 minute easy ride bumping shoulders, practicing drafting closely, and, if you have the luxury of a field/lawn/etc, touching wheels.
Remove the touching wheels part and you reduce your fluency significantly. I'd say someone that "can't touch wheels" would be 70-80% of a Cat 3 field, 90+% of a Cat 4 field. I'm talking normal rub, like in a corner or something, not a swerve at 30 mph across the field kind of thing. I hit the deck in a situation like that and my bike was parallel to the ground before I realized the guy had actually moved so violently to the side.
So that's pack riding.
Bike Handling
Beyond that it's about cornering lines (like if you're cornering/descending solo or at the front or off the back) and some basic bike handling stuff like how to initiate avoidance maneuvers ("counter steer", i.e. push the right side drops to initiate a right side swerve), brake, and bunny hop (for bumps that you shouldn't be swerving for).
Cornering.
Sprinter della Casa: cornering lines
Sprinter della Casa: Tactics - Cornering
Key thing with cornering is that it is FREE FREE FREE FREE FREE FREE FREE. No training, no intervals, no nothing. EPO doesn't do crap for your cornering, you could be on all the steroids in the world but cornering is completely unrelated to that stuff. You corner like **** and you race like **** in a crit. You corner well and you'll be braking to avoid hitting the morons in front of you that can't corner to save their lives. If I couldn't corner I wouldn't be competitive at all in races.
You ALWAYS work on cornering. WHen you drive your car, push a shopping cart, when you're in rush hour traffic, when you take an exit ramp, any time you're not traveling in a straight line you should be thinking of cornering lines. There is absolutely zero excuse for not understanding cornering because it is not a bike specific thing, it's a life transportation thing.
Countersteering - you just have to try it at slower speeds. Do it a few times when you're riding solo, try to get into the habit of making that conscious push when you're doing a rapid maneuver. I don't do it naturally, like in a panic I don't do it, but that's because I don't practice it (I ride outside less frequently than most) and I learned about it only a few years ago.
Braking. This guy linked below is a bit wacky sometimes but his braking and rolling resistance stuff (on rough terrain) I think are pertinent. I'm a huge believer in braking from the drops for power, control, and predictability. I've been next to a really good bike handler on the hoods when he hit the deck because he could neither turn or brake enough to avoid the guy in front of him. That same rider won (Jr) cross nationals later that year, crit nationals in a bike throw the next season, and has I think 5 national titles to his name at this point as well as a neo-pro contract - it's not like he doesn't know how to handle his bike, it's just that if you are using the bike incorrectly it's hard to use it to the max. So anyway this is a much better written/researched thing on braking than I'd ever do.
https://janheine.wordpress.com/2013/...-on-a-bicycle/
With well honed habits I can hang with an FTP in the 210-220w range, at my best. At 220w FTP and typically 1200-1300w peak power I upgraded to Cat 2 in 2010 (and then promptly downgraded after a year "sans" in 2011. The good year, 2010, I won or got second in races averaging about 185-190w@72kg, so about 3 w/kg, even with massive efforts sprinkled in here and there. In 2014, at more like 200w FTP at times 82 kg, very little training, I won a number of field sprints in Cat 3-4 and M45 races. I could do that because I can corner and I can ride in close quarters to other riders.
This is
my favorite 2010 race. Avg wattage 187w. Peak power was only 1200w, but I think I did 1100w for the long sprint. My leadout guy Cliff did 100w avg more than me; I later learned he used to race pro for K2/Proflex mtb. Obviously he did a lot of work in the race.
Just don't ignore the basics of bike handling and pack handling and with your weight/power you should be flying. Hell, if I could increase my w/kg by 30-40% I'd be rocking all day long.