With regards to weapons resting - with machine guns in particular: Machine guns rested on a bipod do NOT climb with recoil.
https://youtu.be/c11N3Q7efo8?t=1m18s
As you can see, the weapon just recoils backwards. The barrel doesn't climb. This is because the weight of the gun is bearing down on the bipod at the muzzle end. MGs are specifically engineered to do this. If you did, you'd see videos of guns climbing up, and their bipods coming off the ground. That doesn't happen IRL.
It's rather frustrating that you can't stabilize your MG with your bipod when resting it on something. The MGs in ArmA are basically useless in this respect because you can't keep the gun pointed at your target for a burst. Instead, you have to fight the gun and pull it back down towards the target, and this doesn't happen in real life. In real life, you hold the gun with a firm grip, aim at your target and just fire. There's no fighting the recoil like you do in ArmA. The gun should vibrate and bounce around the point of aim somewhat creating a beaten zone, but it doesn't climb.