They can bite. Hopefully, if you socialize them well enough, they won't, but if you startle them or they're not well socialized and not used to something, they can bite.

They can be. Many guinea pigs are friendly and enjoy scratches, but it depends on how well socialized they are.

It can be tough if they have darker nails, but having little trimmers may help. If they're white nails, you want to take the white part and not touch the pink part at all. If they are darker, then you start with tiny bits to make sure that you're not going to hit their skin and make them bleed. If you're uncomfortable or don't have someone to help you hold them, we can do it for you. Otherwise, I think some of the local humane societies have $5 events every couple of weekends, where you can bring in your guinea pig, and they'll trim the nails for you.

You shouldn't need to. Guinea pigs do have some waxy stuff in their ears, so you probably wouldn't need to clean their ears out unless you notice that it's smelly or they're really going at them, in which case you should bring them to the veterinarian anyway, and then we'll do it for you. There could be a lot going on. There could be an infection or something like that. So make sure to have them seen by a veterinarian and not take it over yourself because there could be a couple of different things going on. We'll need a special scope to see down into the ear canals.