sounds like fun im itching to go back, maybe in september haha. if you're looking for a big event, you can try to plan for july 7th, for Sevens Day. Or theres just usually places to go every weekend and some week nights for small events.
id say figure out what kind of tuners you want to visit, and see if you guys will plan to stay near tokyo (kanto region) or if you would like to travel down south more (kansai/kinki region).
the trains and metro there are very convenient and easy to figure out after the first day. if you're planning on not travelling far, you could get by just paying daily for subway and train tickets, or you can check out JR (japan rail) for their visitor's unlimited pass if you guys want to go all over the place (lets you use the bus system too).
my accommodations cost anywhere from 25-50 a night. for the most part i booked at hostels and small hotels.
www.hostelworld.com is a good place to start. they're not bad at all, places are always clean, every place usually provides free internet access. another option is looking for what they call "weekly mansions". its basically like renting an apartment for a week. multiple bedrooms, kitchenette....much roomier, and it broke down to maybe 30 something per person ea night.
food's not too expensive there either, i spent maybe 15-30 a day on sit down meals.
i did my hwk more on the tokyo area....tuners out there would be... rmagic, re-amemiya, knightsports, wise one auto, top secret, panspeed, kazama, scoot, spoon, mugen, jun, amuse....given that a lot of them are still quite far apart from each other....90 minutes one direction, 120 minutes another direction......and a few of them aren't near a train station...you could probably take a bus or a taxi...and then walk aimlessly around pointing at a map printout like i did and asking convenience stores how to get there haha. Theres also Tskubua circuit or motegi ring, nikko circuit... the honda museum, the toyota factory tour....asahi or sapporo beer museums..
down south would have Feed, hks, signal, makers7, bride, splash, tanabe, nagisa auto, junction produce, chargespeed...
useful links:
www.japan-guide.com
http://www.gaijinpot.com/
http://gojapan.about.com/
uhm...not sure what else to say....meals are great, no tips, and tax is factored into the menu price. whatever or wherever you eat, you pretty much just bring the check up when you're done and pay.
party and drinking districts = roppongi (lots of foreigners and english speakers, for those days when you just dont feel like trying reallly hard to communicate or miming out what you need hahaha), Shibuya, Shinjuku.
if you guys plan to go out late night, find a place to stay thats in that district so its not too expensive to take a taxi or walk back....otherwise plan to stay out til 5am partying because the trains stop working at midnight.
not sure what else....ask me if you have more Qs
carol