[jiggy2011]

On the iPad is it possible to download an app and somehow cache it onto some other storage medium (i.e a PC or Mac HDD) so you can uninstall it, backup all your personal files and then sync it back over later (via LAN or USB)?

I ask because I was thinking of getting an iPad3 in the near future and was tempted to get the 16 GB model because I have many TBs of storage elsewhere on my PC/NAS/Servers so I'm not going to use it to archive anything long term. Plus an extra £70 for 16GB seems steep when I could get a 64GB SSD for the same.

[noonat]

Yes. iTunes on your desktop machine can store (and update) apps that you are not currently syncing to the device. Then, when syncing the iPad, you can check a box in iTunes to indicate that the app should be included on the device.

[Someone]

I think ~Yes/No~ is the better answer. You can remove apps and sync them from a backup later, or even download them from Apple, but AFAIK the only way to restore an app and its user state ('where was I', login info, preferences, etc) is by doing a full restore of a backup (all apps installed at a given time and their stare, plus all device settings from that time)