Dry food you can leave out for a week, but vegetables you have to replace every day. If your guinea pig hasn't eaten a type of vegetable at all, then don't give it to them again, as they may not like it.
If you leave it long enough, yes. :(
No, get guinea pig food for guinea pigs.
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.
You shouldn't leave your guinea pig alone for 3 days. You will need someone to take care of them.
At the age of 8 weeks
you can't, they are very stubborn creatures (unless you train them). the best thing to do is leave the food in their cage. If the guinea pig is injured (for example, when my guinea pig broke her tooth), you can get a special formula (at an exotic vet's office) to syringe feed them.
NO they need guinea pig food and they need fruits and veggies everydqy.
you can give your guinea pig bunny food you just have to add vitamin C drops into their water, but never feed a bunny guinea pig food!
soil
as long as there is one person there to comfort the guinea pig too eg: feeding it its favourite food there is often no need for drugs as the guinea pig will be relaxed
the guinea pig squeals because it thinks food is in it.
no