Crown, there are two ways. The first way is to bring a Rapid Shield Recharger on a Utility Slot. So if you need some shield, switch to it, and press Z. And if you don't have Rapid Shield Recharger, you can hold C key, so you will transfer your Energy in Shields.
BMTrom, try to search what you want in Google, you can always find it. And if you don't want, wait until you have 6400 kills so you can see on the map x)
The ship that you get with 3201 kills, the "Enforcer" for Aliens, and "Hydra" for humans are good in everything. Longe Range Sniper, Aceleration, Top Speed, Dogfigther, and other.
A tip: If you need many kills, take the ship with more Regular Weapons Slot, and equip all but one of they with "Xandelevium Blasters". The other one that is left, you use Plasma Cannon, Photon Bomb or Laser Beam. Then get some money to buy a good engine, that recharges automatically the Hyperspace, and go to the last sector of the enemies (Using Hyperspace) (Choose one with 1 threat rating), then you keep killing everyone on that sector, and when you are about to die or you have no ammo left, go to other sector (With the same Threat Rating). And if you have 2 lifes left, go back to your Base (Using hyperspace), and with your bounty, you buy another lives.
Doing that, i get from 201 kills to 601 kills in like 2~3 hours.