1) I am starting to get some results from barracks training: report screen has said in the past that dwarfs were sparring. It seems to indicate now that they are fighting and I have had 3 deaths during training. Two were wrestlers that seemed to 'land wrong' (collided with an obstacle) after being thrown and suffered damage that ultimately made them suffocate ... any profit in making a sand floor?
They're fighting (ie. showing up in the Combat reports) because there's no such thing as a sparring throw, and they're doing throws because they don't have any weapons with which to lightly tap each other. You can stop them from throwing each other around by giving them a weapon. A shield works too, as they'll use it as a blunt weapon.
If you do want them to practice Wrestling, then they'll need armour. Leather armour has stopped the injuries for me while I got metal armour made, but if you let them spar in only leather for long enough you'll probably get a fatality. Give the dwarves skull and spine protection at the very least -- a helm for the skull, and a mail shirt or breastplate/leggings-or-greaves for the spine. With this alone you may get quite a few broken wrists and legs, but nothing fatal or permanently crippling.
I don't know if sand is simulated to be softer than stone. If you can easily move your barracks to a sand area, do so. Either it will do no harm, or it will be helpful.
As for the lever issue, I'm not sure if it's been addressed, but raising bridges one tile wide don't visually change when they change states. Either build the bridges 2 wide, or find another way to check if they're up or down. If the area around the bridge is accessible to wagons, check the depot access. You could also try stationing soldiers on top of the bridge and checking the Unit list to see whether they're carring out the station order or complaining about 'unreachable location'.