Requirement of Energy 6 means 147 modules on Normal to save that 1 AP round on turrets and 2 rounds on heavy mechs, along with taking up 3 spaces of inventory.
Stasis -- yeah, you could tech to Heavy 3 and lug it and prisms around for those enemies; or you could just shoot them.
No, one uses maintenance and the other has no prereqs. Maintenance also has the bonus of giving you more charge in your implants, powered armor, and energy weapons, while
gives you no added bonus and is completely replicated by
, which are plentiful enough.
A couple of the weapons are unbreakable, too.