Grats Lohengramm, this is some very sensible and well-rounded rebalancing.
Two notes :
- Be careful with weights inferior to 3, because weight is used as a divisor for throwing distance. In the vanilla game, 3 is the weight of the lightest items, including flares and grenades. Items with weight 2 can be thrown 50% farther, items with weight 1 can be thrown a whooping 300%.
- About the question of heavy plasma having no snap : You could redefine deployments to give pistol/rifle/heavy + basic clips in the first months, then pistol/rifle/heavy + advanced clips, then pistol/rifle/heavy + high-power clips in the endgame. This way, aliens maintain the variety of weapons from beginning to end, yet their firepower improves gradually. As a bonus, the player who researches alien technology immediately does not get the endgame firepower.