Going to see 2 kittens later tonight?

You can definately take them home today if you want. Kittens can be taken from their mothers at 8 weeks so they are fine. Also you could take them home in a cardboard box if you want although if you can get a carrier that would probably be a bit better. As for the genders, it doesn't really matter as long as if you get a male and female and don't want them to breed (which would cause more problems than you think because they are siblings) just make sure you get them spayed and neutered. As for what you should buy for them I'd say food, toys, a litterbox and litter, and a bed if you want them to have one. Good luck with your new kittens!