I used to be really into paintball and play every weekend on a team with some friends. No, I'm not talking about running around in the woods with camo on trying to attack a base or anything like that. I'm talking about speedball. Anyone else play?
The small animals can be kept away with a pet cat. Other than that, I can't really think of anything that will prevent them. Look into like territory methods, like how dogs mark their territory by urinating, maybe the squirrels won't go near it if they smell dog. Just a thought.
You need PC's to root the original Droid I'm pretty sure. I also had that problem :/ But luckily I had an old dinosaur age dell I used. But if you get access to a PC, look on google for 'rooting 2.2.1 droid' and you should be able to find a tutorial/walkthrough.
Cracked cylinder heads are pretty much a dead issue. But if you get it for free, then flip it for a few hundred dollars, you can use that to get an even better car.