Infant stages of booking Japan trip

[Miss_Shell]

Hi
We are currently considering a trip to Tokyo and need as much help as possible!
So far, we have *very* rough guide of what we want to do:

Fly into Tokyo and visit Disney for 5 nights > Kyoto 2 nights > Finish in Osaka for 2 nights and fly home.

So I have a bunch of questions:

- Best time of year to go?
-How easy/hard is it to travel to and from the above?
- Language barrier is scaring me a little, can anyone offer advice (other than trying to learn obviously!)
- Any obvious culture customs I need to know/be aware of? I don't want to accidentally offend the nation

I'm so there are SO many more but I can't think haha,

Thank you in advance