In regards to getting one or two cats..... Personally I would go with one to start with and wait until they have settled and are friends before introducing a third. If you try and introduce two new cats, the cat you have now may get a bit irritated and even territorially which could cause major issues. It's best to introduce cats slowly if you can. When you pick up the new cat, take a piece of bedding that belongs to your current cat to put in the carrier, that way it gets used to that smell before arriving in a home that only smells of it. I would leave the new cat in the cat carrier while letting your current cat smell them through the cage and see how they get on before introducing them.
Another good way to do it, would be to lock up your current cat in a separate room and let the new one get used to the main areas by themselves. They will sniff that another cat lives there but have freedom to discover the place first and become more comfortable.
