1. Pretty unlikely. Snake mites ignore rodents. If there was an infestation in the pet store, they are highly mobile, though, so they could have come in on anything--from a bag of bedding, to a pant leg. Wild snakes are also highly active at this time of year, so walking through an area where an infested snake has been could result in one hitching a ride. It's even possible the snake had mite eggs on it when you got it, and they've just now built up to a level where you noticed them.

2. Quarantine any new animals...but in reality, as explained above, you can't completely eliminate the risk--just be alert, and treat immediately if you ever find them.

3. Be very cautious with the other products--anything that contains toxins, including natural ones, poses a risk of poisoning the snake as well. Use carefully and according to directions.

4. If he's eating, I don't see why you shouldn't feed him, just be sure the rodents don't contact any of the treatment products.

5. See #1...I wouldn't blame the pet store without evidence, and even if you find some evidence there, what would they do about it?