Engineering 5 - max power core.
Electronics 5 - max CPU.
Energy Management 5 - max capacitor capacity.
Energy Systems Operation 5 - max rate capacitor recharges.
Energy Grid Upgrades 5 - reduce CPU needs of pwr modules.
Shield Management 5 - max shield capacity.
Shield Operation 5 - max rate shield recharges.
Hull Upgrade 5 - max armor.
Repair Systems 5 - best repair modules.
Mechanic 5 - max hull strength

Class 1 = Hideaway or Drone Cluster (easiest)
Class 2 = Burrow or Drone Collection
Class 3 = Refuge or Drone Assembly
Class 4 = Den or Drone Gathering
Class 5 = Yard or Drone Surveillance
Class 6 = Rally Point or Drone Menagerie
Class 7 = Port or Drone Herd
Class 8 = Hub or Drone Squad
Class 9 = Haven or Drone Patrol
Class 10 = Sanctum or Drone Horde (hardest