I can honestly say I have never saw the need for a removal tool. Just stick you hand in an overlap and pull down a bit and the siding will unlock.
Yep. Ive used it a few times on tricky locks, but most the time, just getting rough with it works. (The head of a nail will work too.) Its very forgiving, unless you live in the arctic.
Air compressor and siding nailer for reinstalling.