Parasites should not be a problem, and if there are signs of them, then these animals have not been kept in clean conditions. Animals get lonely too. However, do not keep two males together as they will continually fight. Housing Guinea pigs can be kept indoors or out, but as a family pet, you may want to consider keeping yours inside. Guinea pigs can live peacefully with rabbits in outside hutches that are protected from the elements and predatory animals.
Most pet stores have a wide variety of cages and aquariums to choose from.
Cages are easier to spot clean, while aquariums are neater as shavings do not come out the sides. Your guinea pigs cage should be cleaned weekly, or more often if necessary. I clean ours twice weekly. Most cages have slide out removable trays where the dropping will fall from the mesh floor above. Guinea pigs tend to use the corners of the cage as their toilet, so pay close attention to those areas when cleaning to avoid possible parasite infestation.