For the wire connection it's actually impossible (and certainly will ever be)
The weapon and hands are separated models with separated bones and vertex weight, so putting something that link both will looks really odd.
The wire would move independently from the hand and just follow the Gun. The only way to do it is to remove any animation from the hud hand... Which will make you look like a turret. It's funny cause I wanted to try something like this for the flamer, but I quicky understud that it's not possible (and also noticed that wire use alot of tris

) .
The other thing is that it would mean no reload animation possible, magazine reloading makes the reload time a bit more visual.
Something that can be done to 'explain' the unlimited ammo (which is not specially necessary) can be an ammo regenerator on the arms. When a magazine is empty, the hud hands clip it in the generator, and take a second one that is stocked (can be different for each weapon, like shell going out of the palm for shotgun). It would also require a second reload animation (that have to be added by quin) to alternate the magazine position in the generator.
The prob. with this is that it will require a full hud hand redesign, that is not planed for the moment.
Finally, it's a bit complicated and time consuming, I suppose new gun models, or new actor models will be more appreciate for the moment, isn't it ?
There's other stuff not realistic in the game like the pistol firing 5 bullet with 2 shell, but I don't think that matter that much.
Also, I don't think reload should drain impulse, as it's only there to balance unlimited ammo and forbid no stop spamming. Keeping the impulse for parkour is better IMO, but if it's a vars off in default gameplay I don't care much.