Guinea pigs like the company of their own kind, but males should never be left together if they can get e scent of a female. They will fight. Never put more than one make with females for this reason. There are no limits to how many females can live together. However, guinea pigs are fine with just human company, as long as they have sufficient attention.
If the guinea pig is just roaming around the house without protection, then probably. if it's in a locked cage, then it should be ok. a little scared, but ok.
You can feed them both guinea pig food. Don't feed the guinea pig the rabbit food or it will be sick. Rabbits are ok on guinea pig food.
It is reccomended that guinea pigs live in pairs or more. it is ok for you to only have one but only if you have the time to socialise and communicate with him/her. many people that own one guinea pig say that it is easier to build a strong connection and happy relationship with your guinea when it is on its own. please be aware that if left alone and not petted, socialised with or given floor time a lone guinea pig will become very depressed. Make sure you have enough spare time to spend with your piggy if you choose to get one. Also try to find a guinea pig that is already living alone as taking a guinea pig away from its siblings can be saddening and stressful. I would also recommend that you get a male guinea pig if it is to live alone as they cope much better with living alone.
Yes, tomatoes are great for guinea pigs.
yes its ok to give your pig grains but try not to give it too many.
Yes
Not if a guinea-pig eats it, as you have put in the question. It's okay if a guinea-pig chews a piece of fabric, because it will grind their teeth down, which is a good thing.
It depends. They certainly wont be aggresive, but if you do, make sure to spay and nueter them.
no if you feed them it, they have 99% of dieing
guinea pigs dont fart, they have no way to remove air from their bodies.
a guinea pig and a mouse aren't the same the guinea pig must have its own type of food like alphalpha pelets and hamsters should eat seeds,nuts,etc. Seeds and nuts are like poison to a guinea pig if the guinea pig and mouse are just eating alphalpha pelets (not seeds) i would say its ok.
its not the best idea coz guinea pigs like getting used to their habitat, and they hate being in cars U nit wit the official hand book says that it is OK