You can install any version using AppStore++ which is available when you jailbreak. The older the phone, the easier the jailbreak.

You can always download the app version that works for your phone using the Purchased section... the only real phone I have yet to be able to do this for is the iPhone 4 which did not have 64-bit apps.

My iPhone 5S and beyond all have access to every app that is available for 64-bit OS. It's often an older version of the app but that's kinda the Apple burden.