Buying tickets for trains in Osaka/Kyoto?

Hi, first timer going to Japan here. I'm going to Osaka next week with my family of 7 people. I'm basically in charge of our vacation, and have already had our routes mapped out and everything, but I only have one concern:

Is it going to be very difficult buying tickets for a first-timer in Japan who doesn't really know Japanese? We'll be doing a lot of station hopping (going to USJ, Osaka Castle, the Aquarium, plus trips to Kyoto/Nara and the like) and I'm very concerned about the convenience of buying tickets and using the train. I know the routes and stations we're supposed to be going to, but my only problems are the ticket buying and getting on and off the train itself. Are the ticket vending machines in English? How about the signs inside the train indicating which station we're stopping at? Thanks for any help!

I recommend to use a Icoca IC cards! They are very easy to use:
http://www.japan-guide.com/e/e2359_003.html

Don't worry, ticket vending machines all have a prominent "English" button and are pretty easy to use. Stations usually have clear English signage, and there are always people on hand to help. I was a bit daunted before my first trip, but was very pleasantly surprised by how easy organising transport is.