A hint to help with those exos. Create bleeder runways if you can. Have your hardened shield world take the wave defenses, but make a 'runway' for the exos to come down with long range turrets, minefields, and fortresses. When you get it working right you'll usually only be handling the big ships on the shieldworld as your bleeders clean off all the little stuff as it passes through. Just over-build short range defenses on the first bleeder world, a lot of smaller fleets will 'break off' and go for the fortresses/snipers/etc.