[Firebird]

Travelling inside Tokyo is not expensive, i also think 1000yen a day should be enough (budget minimum 1000yen each way from and to the airport).
6000 for food is enough. You can even have really nice food for that but i hardly ever spent more than 1200yen on lunch and a few 100 on breakfast. All you can eat dinner (in all kind of variations) usually go around 2500 or up. If you´re friends lived there for a while they will know good places that are not to expensive.

I lived close to Inokashira Koen (Park) near Kichijoji and this park is beautifull in Autum. On Saturdays the park has an "Art market" wich is nice to walk through. There are people selling their pictures or postcards and some people play music while you can watch Japanese couples paddling over the lake with small boats. I loved the atmosphere in this park and its only a short walk from Kichijoji Station on the Shibuya line. I´d definetly recommend half a day up to a day in that Area (Kichijoji). If youre friend is Japanese he will know the area.

For clubbing you can either go to Roppongi ( wich is "the foreigner area) and there are some clubs in Shibuya as well. I´ve only been in Roppongi once but i didn´t like to be aproached all the time (come to this bar or have some all you can drink here,...). I´ve been clubbing in Shibuya once in Club Asia wich was ok. Ask your friends for more tips.

For the other stuff just use the search function on the forum, as the question on what to see and do in Tokyo has been asked and answered alot of times

Firebird