Re: When the word 'bat' becomes a bad word
You'll have to seal the bats out of any place you don't want them roosting. That means plugging any hole greater than 1/4". Where you need to have vents, use 1/4" hardware cloth (it's heavy-duty screening material, available at any hardware store or home center).
Install a bat-chaser in the attic. It's an electrically-powered device that emits an ultrasonic sound the bats don't like. I don't know if they really work or not.
To encourage the bats to move elsewhere, build some bat houses and place them on your property away from the house. Just do a web search for "bat house" and you'll find plenty of information; you can build them yourself (they don't have to be fancy).
You can probably do the cleanup yourself. It will be stinky, dirty, messy work. Get a disposable protective suit (Tyvek-type) and a respirator. (I think you can get these at home centers in the paint department.) Get heavy-duty trash bags to contain the waste; if you're paranoid you can double-bag it and seal the bags with adhesive tape.
Just be very careful around any electrical wires; if the wiring in your attic is on porcelain insulators, you may want to shut off all the power when you're working around them. That old wiring has very brittle insulation; avoid making contact with it. A hard bump could easily break the insulation off.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.