IOS – How to enable cache in iPad

I agree with Thiago that this shouldn't be a legal issue. If you have 20 iPads and want to sync them all to one computer, you might want to consider looking into getting a cart or cabinet that syncs and charges all of them automatically. If you're interested there's more info available at www.ipadcart.info

At the moment, you can't really do this. Although I suspect that Apple is looking to integrate iOS and macOS in the future so that this sort of thing can be done (purely speculation).

GarageBand on the Mac is different from the iPad version (it's more comprehensive) and it has been available on macOS for far longer than on iOS.

It is possible to run iOS apps in the Simulator app that comes with Xcode. However, it's not as simple as downloading an app from the App Store. You'd have to get the source code for the app, compile it in Xcode and run in the Simulator. Most apps being closed source, this won’t be possible!