Welcome to the Order! You probably want to switch to the Anubis heavy fighter; it's a fine piece of equipment, and quite reasonably priced. Load it up with Pyros or Lugers, and if you couldn't buy a Luger turret or pyros turret before you left for rheinlnd, one of the old Angelito mk I turret; it's better than either of the Order turrets. Do not buy the Order Thruster; the Advanced Thruster you already have is much better. Also pick up a torpedo launcher if you don't have one yet. You'll be taking down a bunch of stationary targets in the next few missions.
In Buffalo, sell the H-Fuel. If you have the money, which you should, buy Cardamine. Now get ready for some difficult fights; you'll be going up against ships with very heavy weapons, including defenders with nomad prototypes, powerful class 7 guns.