1) I like to go heavy on fighters, because fighters counter the kinds of things that planets typically have to worry about (mainly siege frigates, but also scouts and bombers). If they show up with the kind of thing you need bombers to deal with, you'll probably need a mobile fleet to help defend anyway. I always like to keep a couple around anyway. 66%-75% fighters. This could change if your opponent is, say, spamming heavy cruisers. 2) I like loose formation. When you are attacking an enemy would with a mixed fleet, and you tell them to go somewhere / attack something all of the frigates will fall in on the capital ship and they all go to their next destination in formation. "Loose" will let them break formation and engage those targets without waiting for the (SLOW) capital ship. If you had a fleet of carriers with flak frigate escorts, you might want to use a different formation, though... 3) It's good for a) bringing your fleet back into your static defenses without having them run off again, backing off and letting those pirates travel through your systems so they can hit someone else.