Bicycle Mechanics - servicing questions

When I bought my bike, it came with the bonus of a free service in the shop. I'm leaving it in for the first one on Friday. My questions are

1. What does a service commonly entail?
2. Do people service their own bikes or have their bike mechanics do it for them?
3. How often should I service my bike (or have it serviced) ?

1. Adjust brake and derailleur cables, maybe check bearing adjustments.
2. Some are shop people, some are home maintenance people. The "I'm leaving it in ... on Friday" part is one of the reasons for joining the latter group - you don't have to leave your bike anywhere, you do the maintenance when you want, and you don't lose the bike for days/weeks.
3. You'll find about 387239 threads on this topic in here, but answer is, it depends. If you're real anal retentive, you'll take the whole bike apart, clean every part and put it all back together after every ride. If on the other hand you have a life, a minor tuneup (clean chain/drivetrain, verify cables + bearings) evey 500-1000km and a major one (minor + bearings repack) every 2000-5000km should do it.

A new bike has to be broken in, especially the cables and the wheels (the spokes will stretch and the wheel will go out of true). Before you drop it off, be sure you put some miles on it and put it through its paces so everything is broken in.

thanks for your replies. I just use my bike to commute, so leaving it in on Friday isn't a problem. I usually walk or get the bus anywhere I have to on the weekends. As for having done a few miles, I have probably only one about 500 since I got the bike a few months back. I also want to have it kitted out for winter, with good lights and mud guards etc. I didn't need those in the summer so I thought I'd combine the two tasks and get the shop to fit those after servicing

This isn't a car. There is no general "service". You adjust things that go out of adjustment and you replace things that are worn.

Ask the shop, exactly what a "service" entails. Have them write it down. If they can't explain to you what a service does or what precisely it means, find a better shop.

Paying for a general tune up basically means you're burning money. Find out exactly what kind of things is wrong or mal adjusted. And fix them. If you can't fix them yourself, tell the LBS exactly what needs to be done and let them do it.