Hello!
I'm strictly speaking of the 3 inch ordnance rifle which will be the first useable cannon in WoR. It's limber chest content will of course differ from those of smoothbore guns.
You can hang back, yes - if you wish to spend the time and manpower hauling the guns and their limbers back. That is entirely up to you - it may prove to be a sound tactical choice sometimes.
Note that the rounds in the limber chests are limited in numbers. Once you've used the available 25 rounds (10 shell, 10 case and 5 canister) of the half section of the limber chest (the removeable tool tray, exposing the other half of the chest will be a future addition to the artillery and not part of the release) you are out of ammunition. So if you have any plans regarding using the cannons for their canister firepower only you're going to be limited to 5 shots per cannon/limber per round.
Yes, enemy artillery crews can use captured cannons/limbers. Infantry cannot but they can disable the "battery forward deployment" option by getting close to the initial deployment area of the battery in question with a few men. This area will be visible via the caissons in place there (not moveable) even if the guns and limbers have all been pushed away. We've opted not to allow infantry to interact with the cannons or limbers in any other way as we do not wish to see a meta develop where two thirds of the artillery crews are actually infantrymen (whom of course will be much better suited to defend against a surprise attack with their rifles and bayonets compared to the low damage dealing ramrod of the artillery crews).
We want the choice of sending infantrymen over to defend an exposed arty position to happen out of concern for the arty crews ability to manage man to man fighting.
- Trusty