I'm also a fan of getting littermates if you can afford them, but it sounds like you've already picked the kitty and fallen in love.
So that may not be an option, anyway.
I agree that most cats are fine as single kitties and that some are happiest as single kitties. I will say that watching two cats interact is endlessly entertaining, though!
(Aside: I think that if you wanted a second cat, the move would be the perfect time to get one. Weird as that sounds, I think the existing cat may be more accepting of the new cat in the new environment, since they'd both be entering a new territory rather than on cat intruding on the others' already-existing territory.)
I could be wrong but I wouldn't worry about the heartbeat cuddle thing. I think the kitten will be old enough not to need it.
Generally speaking the decision about where a cat will sleep is made by the cat.
You can put out a bed, but she may or may not sleep it. (She may even move it to her preferred location -- isn't it Holly who drags her bed to wherever she happens to decide to sleep?)
Many people are big fans of sleeping with their cats. Me, I'm fine with it as long as I'm sleeping
with my cats. When I'm awakened at 3am because Misty is patting my face with her paw asking to be petted (Saturday night) or because Stormy has decided she needs to climb onto my pillow and eat my hair (last night) then I'm not so keen on it.
I'll warn you that cats have very individual responses to being in a new home. Depending on the cat, the newcomer may decide to spend several days straight in hiding (when my housemate in grad school got a new cat, the cat didn't come out from under my bed for 30 straight hours, even to eat, and didn't venture out for more than a few minutes for at least a week). So don't be surprised or offended if it turns out Libby would rather not have company for the getting-used-to-her-new-home period. It's not personal, some cats are just like that.