Jensen,
It is really important to get the starlings out of your barn! They can carry MG & MS and also they carry internal and external parasites. You need to try and cover any holes with hardware cloth and shut any doors that are left open. Runs can be covered with netting to prevent the starlings from getting in and birds of prey from getting your birds.
For lice, the best thing I have found is Absorbine Brand Ultrashield. It comes in a black bottle and has natural and synthetic repellents. It has a 17 day hold, so any lice that hatch during that 14 day period are killed or repelled. You don't have to put it on the skin, so there should be no problems with egg withdrawal or overdosing and killing your birds.
I spray under each wing, the back of the neck and the butt fluff. It works wonders and you shouldn't have a problem with lice if you spray your birds in a timely fashion for a month or so. But, if you have birds coming in, you could get reinfested....