Tarmach, I'll take your questions in order
1) 100 hours must be P1, 5 hours of TT must be at night (i.e. get a night rating and you've got the 5 hours night!)
2) Yes, most schools require just a PPL and a class one medical
3) No, you can go on an integrated course, but you will re-learn flying from scratch so it may be a waste of money
4) Try the adverts in Pilot Magazine and Flyer Magazine - Bristol, Four Forces, Coventry and PPSC are some of the well-known distance learning schools. Do a search on 'distance learning' in here as well - there's been lots written about it. A lot of pprune wannabes are going the distance learning route. It's not easy I can tell you (nearly finished my course with Four Forces).
I also need to correct WXMan slightly - what he has said will give you a frozen ATPL/IR - which means a CPL/IR with passes in the ATPL theory exams. This is the airline first officer qualification. You can also fly single-pilot types professional with this qualification.
The full ATPL/IR, needed for airline command, requires 1500 hours TT (inc. 500 multi crew, 100 night) and a skills test on the type you are flying.
[This message has been edited by foghorn (edited 01 March 2001).]