It should be relatively easy to add more properties to the table that is displayed under add combatants. Which ones do you want to see there?
A Basic Speed entry that influences the initiative would be very helpful.
Properties for weapons + dmg, skill and damageresistance (=>armor) would be nice, too, but they need no "quick edit" entry - in my eyes at least.
Probably. What is a posture-marker?
There are several different conditions in gurps: Dead, stunned, unconscious and the postures: standing, crouching, kneeling, crawling, sitting and lying down. A posture marker would be sime kind of flag/label/marker that tells me which combatant is in which state/posture.
I think adding the maneuvers would be a good thing, too, since they affect a lot of stuff in gurps combat. It's quite important to have a good overview over the chosen maneuvers because of the great effect some of those have - the All Out Attack for example prevents you from defending at all for a complete round.