Mountain Biking - Some stupid questions...maybe

First of all, I finally went clipless. I got the Time ATAC Aliums. I really like the feeling of being clipped in, but I have been having a hard time getting out in a hurry (probably just need more practice). Do the Times have a "break-in" period of some sort?
Also, I haven't really had the chance to do much trail riding since it has been pretty muddy here, but how do you guys ride clipless pedals on the technical areas of the trail? Do you stay clipped in or do you ride unclipped? If you unclip how do you stay on the pedals? I know the Aliums have a larger place for your foot than some of the other pedals I was looking at, so how do you prevent your feet from slipping off and either eating some handlebar or crushing the boys?
I just got my new seat in. I decided to go with the WTB Race Speed V. It had pretty decent reviews and for only $20 at supergo, I just couldn't pass it up. I just got it last night, so I haven't had much time to ride with it. But when I was putting the seat on I noticed these numbers on the rail (ranging from 0 to 30, I think). What are they for? I didn't see any mention of them on the packaging I got.

I stay in the pedals all the time. They're really too small to ride on them without being clipped in. Practice makes perfect when it comes to getting out of them in time. Grassy areas are good places to practice. Just clip in and out a bunch of times. If you want to practice panic release let yourself start to fall over and then try to get out (this is why grass is good). The heel swing release is pretty natural and becomes second nature pretty quick.

Time pedals won't really break in, but the cleats will wear. When the cleats wear it gets a little easier to unclip. When your feet start coming out too easy it's time for new cleats.

The little numbers on your saddle rails are just measurements. They're nice if you want to play around with fine tuning saddle placement because you can make note of small adjustments. They're also good if you move your seat or take it off and want to get it back where it was.

congrats on good judgement re pedal choice

pedals/cleats won't break in although as PT says once the cleat wears you may discover a little slop. No adjustment necessary which is what makes the ATAC zyztem so great.

do what the friendly manual says and practice clipping/unclipping 10 times each foot - makes it easier when under pressure (traffic/trail/obstacle) to dab if necessary but remain clipped in for better control.