Finding the theater is really easy, it's quite close to the station.
Tickets are 3000 Yen for men, 2000 for women if you want to see Team A, K or B. Research Student shows are 1000 Yen less.
Getting a ticket is a bit more complicated (and you have several option when coming from far away). You can't just go there and buy one (unless you play stupid and are lucky - it worked for some). Knowing Japanese helps a lot.
Just go to Stage48 - All you need to know can be found / asked there.