Hi Cacret, welcome to the forum! 
You definitely have a zoo at home. 
I am not an tarantula expert, but I have done some homework for your questions.
1. It seems most people feed tarantulas slings with mealworms, superworms, silkworms. Basically worms. Some people claim they will need pre-killed food, like dead baby crickets. It depends on the individual tarantulas. One might eat the food the other won't touch. 
2. It might not be a good idea to keep more than one tarantula in the same container. So if you decide to get two tarantulas, please get two separated containers for them.
3. A red rump is a fairly docile species, but it can also become aggressive on occasions especially when it feels threatened. It is not recommended to handle your tarantula very often as they do not need human interaction. If they bite, it is like a bee sting.
By the way, I look forward to see some of your pets. The fish aquariums are particular interesting to me as I am a fish guy. 
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