As for putting on gear: there's no rule that says you have to put on gear standing up. We do that in our OW classes so that our students know how to do it, they have that option
Interesting. I've never even seen that done and it would never occur to me to try it. It there was nothing to place the tank(s) on I would sit on the ground to get into the rig and then stand up in it. I bring along a small folding work bench if I'm going to do a shore dive locally, though.