Tokyo is a very big city with lots to do, so there will be plenty to keep you occupied for 2 weeks. I'd recommend doing day trips to other nearby places like Kamakura or Mt Fuji if you can, because as interesting as Tokyo is, it's still a modern city, and being able to escape a couple of times to see a more traditional/natural side to Japan would give you a nice break! Trains are the most convenient form of transport, and central Tokyo also has a very extensive (and confusing!) subway system. Transport isn't particularly expensive unless you're travelling long distances. If you are planning on doing long distance trips to see other cities, then I'd suggest getting a JR Rail Card, as it gives you unlimited travel on all JR trains (Japanese Rail) within 1, 2 or 3 weeks. Definitely worth it considering a return to Osaka on the bullet train costs about the same as a week pass.
If you're going to Tokyo there shouldn't be too much of a problem with you not speaking Japanese, but I'd still suggest to at least learn some basic phrases because very few Japanese people speak English, even in tourist places. Summer is very hot (and humid) so be prepared for that too!
Can't really think of anything else. I live in Japan, so feel free to ask if you have any questions 😜