Yes, maya is the perfect tool for this i think. And yes you will be able to do all this in maya, but of course photoshop and something for post production would be useful as well.
How hard?..hmm..not verry hard...but time consuming..people say that you need around a year or two to get good at maya. But Since you can concentrate on just those aspects that you need, you should do much faster, few weeks maybe....
If you have 64 bit then get maya 8, otherwise i'd say get maya 7, as i heard rumors that it is better for animators then maya 8(the problem is that its 32 bit), and besides that maya 8 has very few new functions, and even fewer are really useful, and not super-advanced-hardcore users will most likely never use these functions anyway.