Accessing movies on iOS devices?

I have read various forums but am still a little confused about the use of iCloud and iTunes to access videos.

We have an iMac at home and 2 iPhones. We will be travelling next year for 3 months and would next like to purchase an iPad. I have been trying to work out what I can store in iTunes and iCloud. Ideally I was thinking that I could get away with purchasing an iPad with a small amount of memory (16GB or 32GB) if I could access movies/TV shows while I am travelling and change around the files downloaded.

From my understanding, you can access movies via iTunes if they were purchased. If I have downloaded movies via Handbrake and added them to my iTunes library, will I be able to access these while travelling? What can I store on iCloud?

I rang the AppleCare team and even the guy I spoke to wasn't entirely sure?!

Any extra info would be appreciated. Thanks.