What is a "stand off" ship?
Like the Beijing. Able to take hard hits while giving it back at close range.
And for anti-missile/small ship do you think just having the gauss turrets will be sufficient for the small ships or should they have a main weapon of some sort?
Gauss are good, but they would need a main weapon, like a pair of fast firing rails, a laser turret, or some small missile batteries.
As for strikecrafts, why use them when you can use missiles? What are some guidelines for building them? What are the different types I should make?
Extend the range of missiles, stealth attacks, etc. No armor, max power engines, as little cost as possible. You want 3 main types. Small missile armament (size 1-2), large missile armament (size 6+), and beam.