Thanks for playing!
Tweaking the upgrades and adding some options for the sidekick slots is planned for the Bits and Bobs update, if we ever get there. Some will be limited ammo power weapons, but the plan is for lots of variety. Weapon types being more effective against certain enemies isn't something I've considered before, but now I want to look into it. Improving the variety and depth of gameplay is something I do want to tackle in a future update.