The problem was that the heatray was so completely devestating on, say, a jump comm if you just jumped directly on top of an enemy comm or other heavy. It's 0-range damage was so obscene you would burn him down in seconds, while still being a reasonable anti-swarm weapon.
As a response, it was simply owled. I think there is a balance point for it which would be better, especially since being at 0 range with an enemy comm means you take the full explosion damage.
The delay between weapons would be something like -another- state button, because we cannot make this default: Often you want to get out all your damage in a high alpha burst (say when fighting against a heavy unit with a double shotgun + disruptor ammo recomm, then jumping away before he can critically damage you).
Multistunner stuns multiple targets. AoE. So. Yeah.
The Machine Gun should benefit fully from range modules. It's weapon velocity is more than high enough to hit well beyond it's max range. However, like all ballistic weapons, it also gets a range bonus with height (like jumping or being up a hill).
The Disruptor Bomb is popular enough that I don't think it's a problem, it's great when stacking with other slow weapons (like disruptor beams or Ammo) and is good with recomms who can slow down and escape from a swarm trying to overwhelm them.
P.S. Beamlaser is almost all you should ever use if playing seriously, sometimes maybe shotgun for 5% cheese cases.