I'm not Dr. Dave but here's my unrequested thoughts:
Since you brought it up...
"not driving 4 balls to rails on a break shot."
YES. This is hard to adjudicate, discriminates against people who might not be able to generate that amount of force, risks injuring the equipment, and adds no fairness to the game. If the rules for a particular game don't make it advantageous to hit the rack as hard as can be done with control, expect people to try game it. So, make the rules make it advantageous, and there no reason for this rule.
A better player is more likely to get out if the balls are spread out. In our town leagues with no break rule, the "lesser" players often think it's smart strategy to just barely hit the balls and leave a clusterf#$% near the spot. In that rule set, yeah it is strategic. But it makes for boring games... the better player is going to break them out and win anyway. For two "lesser" players competing, they are scared as hell to bust open a rack so their games go on 3X longer than they would if they broke harder. The balls are just a mess and neither player has the skill to break them out. Years ago I used to do this but then at a certain point I realized it was limiting my game.
If I play someone that breaks like this I just punish them like they've never been punished before with stupidly easy safeties freezing them to the rack. The game takes 5X longer but it's funny to watch them sweat at never having a shot. This ain't straight pool so a break should be somewhat forceful.
If a rack is tight it's pretty dang easy to get 4 balls to a rail. I mean, VERY easy. You can still have a defensive break and a clustered mess with that rule. Now in Ultimate Pool 8 Ball I believe you must have 3 balls past the center line of the table or it's a re-rack and opponent breaks. I love this rule. It stopped all the weenie breaks that were so common from scared players and really sped up the game. I hate to be a dick but I've called foul on illegal breaks every time I remember it. The match is on a 30 minute time limit, 30 second shot clock and it's handicapped, meaning some guys have to spot 3 games... that's tough under the time constraint. You need a decent spread to even be able to do that, thus the rule.
"not having a foot in contact with the floor during a hit."
I think there might be a better rule. This is obviously discriminatory and biased to certain body types.
The only body type I could think where this is the case would be someone with a physical handicap. Missing limbs or riding a wheelchair. There are usually exceptions built into any ruleset for this. One of my friends plays in a wheelchair. She's a hell of a player, the only "limit" she has is that she had to get good with a rest/bridge for some shots. She has, and she regularly beats some ass.
"not driving a ball to a rail after ball contact."
This rule is a proxy for a different undesired behavior (tiny safeties). I don't see any reason to have a rule which makes a simple shot which falls a bit short of the pocket into a foul as opposed to a miss. Calling it on an opponent seems amazingly petty.
Thank you kindly.
It does seem a bit petty. The thing is, one could purposely do this and give the opponent a really stupid angle to try to get shape. Basically leave them a shot with no future. I do this all the time (after legal rail contact) and you'd be surprised how effective it can be. When teaching strategy I've named this particular tactic "poisoning the waters." It's a close cousin to "scratch traps" which leave a scratch near the tangent line that is surprisingly hard to avoid. The placement of "scratch traps" can be really dependent on who you're playing. Do they draw most of the time, do they follow, do they shoot hard, do they not recognize secondary caroms? Set the trap accordingly. And if possible do it multiple ways, it they can draw out of it they may not notice the "fat pocket" carom leading the CB to doom. Very effective.
I guess why I'm mentioning these is that there is a lot of "underhanded" aka smart things going on for strategy. Without the proper rules, things can and will be exploited. The rules are to protect you from the cheap shenanigans. Things like on "in the kitchen 8 ball" and a chicken shit opponent just shooting the CB into the pocket to make you kick at the 8 ball. In that particular situation on a scratch, if all your balls are in the kitchen, the nearest to the line spots on the spot and you shoot out of the kitchen. This rule makes "kitchen" rules not as exploitable to chicanery. It was the rule forever but somehow it was one that got forgotten or never imported to most bars.