you want your wetsuit to be tight. as you stated it works by trapping water between you and the suit. the neoprene is an insulator and is what actually keeps you warm. you will feel cold when you get out of the water as the water on the outside of the suit evaporates. the heat to evaporate the water has to come from somewhere. surfers use suits that are slick on the outside so the water rolls off the suit instead of having to evaporate each time they get out of the water.
i have several suits for diving, sailing...
i have a 5mm semi dry suit which is actually a wetsuit with baffles in the sleeves and legs that slows down the water. i have been to 90 feet and surfaced after 20 minutes and still been dry around the torso. it is way too thick for sailing in tampa. it is useful because at depth the suit compresses and causes the insulation value to be reduced. for sailing (in tampa) i have a 1mm suit that i wear under a henri lloyd hammerhead top and anaconda trousers. the trousers and smock have no insulation, but keep the water off of the suit and reduce the evaporation. the suit is for the occasion when the boat flips and the water is a freezing 58 degrees. i have worn it in 60 degree air temperatures and have been very comfortable with only a bathing suit and rash guard under it. my wife (who gets cold very easily) has the same setup and it also works well for her.
the cloth on the inside helps to keep you from bathing in sweat although you will likely still need a rash guard to keep from chafing in the armpits and back of your knees. like i said earlier, the cloth on the outside serves to hold water on the outside of the suit when you get out of the water (this is bad).
as far as bending over without being launched, you are pretty much right on target. tight is good. cutting off the flow of blood to your hands and feet is bad.
by the way, a neoprene cap is one of the best ways to stay warm (besides a wetsuit). you lose something like 10% of your heat from your head due to all of the blood vessels.
dave