How do I organise iTunes purchases/content after moving abroad? Please help...

Question

Please can someone advise in simple terms, I am so confused!
I have recently moved with my young family from the UK to the USA. We are hoping this will be a permanent move, but this is yet to be confirmed. We will be visiting the uk hopefully every year and no doubt take the phones and iPads with us. Between us we have:
Ipad 2
Ipad minis x 2
Apple TV
iPhone 4s
iPhone 5c
All my iTunes content is stored on my hp laptop, including many CDs and DVDs that I converted to an apple format. Purchases in the uk include 10 albums, 10 movies, 1 tv show, 27 books, a gazillion apps (most of those free, apart from I know I purchased minecraft and the kids have spent hours creating worlds on there!). Most of all this is for the children. I don't tend to store any content on the devices themselves unless we are planning a long trip. We tend to rely on wifi and home sharing to access all content from my laptop.
I've just started to look at changing the iTunes Store location/credit card from the UK to the USA. I went to an apple shop to help me do this to make sure I was going about it the right way, I even purchased frozen movie from iTunes Store whilst I was in the apple store, to check it worked. It did, but on the device I updated - ipad 2 - I can no longer see the movies or music that were there before. I've refrained from changing any other devices as yet. The apps all seem to be there however. (I understand that some of these apps may not get updates if I don't change to the USA iTunes Store, since they were obtained in the uk).
I basically need to understand what options I have in terms of easily being able to access all content (whether converted or downloaded content) ideally via homesharing, as the kids are used to that.
1) in settings do I keep the uk iTunes Store and uk credit card linked to it, and continue to make purchases from there (is this even possible?) Would purchasing a uk VPN help with this?
2) in settings do I convert to the USA iTunes Store and USA credit card - on all devices - and if so, how can we access all our content? If this is an option I would greatly appreciate instructions on what to do.
I think one option would be to just change the country/credit card details in settings each time we wish to access something from the 'other' store - but this isn't really practical with all our devices and 2 young kids who just wouldn't understand why they can't see all their movies in the cloud! I don't have time to permanently be switching details on their devices all day!
Many thanks in advance for any guidance on this. I really want to get everything working smoothly.

Answer 1

You can redownload most iTunes purchases by:
Downloading past purchases from the App Store, iBookstore, and iTunes Store
That is sometimes refured of redownloading from iCloud.
If the media is not current available from iTunes/APp store yo can't rdownload it. In the USA, ringtones and audio books are not redownloadable.
For complete list see:
iTunes in the Cloud and iTunes Match Availability