Some interesting points. I don't have the research to discuss all of them, but I'll touch on what I can.
Regarding grooming, this is somewhat explainable. Some people grow facial hair at different speeds than others, and some people are particular about sharing grooming supplies. Especially when things like that are hard to come by, I could see guys like Abraham being hesitant to let anyone touch their razors.
Regarding walker strength and general deadliness, I agree. I feel like the creators will "powerplay" zombies for certain scenes just to create tension. There were a couple times in the last episode where experienced survivors had to seriously struggle against walkers that really shouldn't have been a problem to them at this point. They know better than to get caught off guard like that by now, especially by something as predictable as a zombie.
Cars should definitely be more common. When "it" first happened, a lot of people died in their cars with the engine running (emptying their tanks), but a lot of people were also killed while shopping or in their homes. This means that cars on the highway will mostly be useless, but parking lots should be ripe for the picking. Surely someone knows how to hotwire by now?
Transformation time could vary based on a lot of factors. Remember the bite doesn't transform the victim, it just kills them like a normal (but very quick) infection. General health, bite location, and blood loss are major factors, and maybe some zombies have more toxicity than others. I let this one slide.
Speed of zombies could vary based on how agitated they are. If triggered by loud noises and fast motions, they will start to run and get more aggressive. Like in a recent episode when the group was casually walking in front of a slow horde until Sasha started getting all stabby and provoked them.
With Noah I definitely see him limping. He can get around but is more or less permanently hobbled. The suggestion seemed to be that with medical treatment and bed rest (neither of which has been available to him) he could be improved.
Carl is.. weird. You got him there. I think they just started writing him a bit better in recent seasons. They had him going through a sort of Rick-esque character crisis for a while and he went from daddy's boy to psycho to angsty little shit to normal teenager. I hope he stays this way because wow.
I've never seen them drink contaminated water, and regardless of zombie contagion, nobody is going to drink from that nasty corpse-filled well. Would you? However I am surprised that nobody is ever concerned about getting zombie gore all over their open wounds. I guess it's not supposed to be blood-borne.

So my point is that yes, they occasionally exaggerate or understate certain things to serve the story but most of it is explainable and not really plot-breakingly inconsistent.