I can't answer all of your questions but a few. Females do tend to be larger. If the 6-9 foot range is what you're looking for, you'll want to look for a BCI, instead of a BCC.

I could handle my baby RTB almost every day and he will still eat f/t or live flawlessly... But he can be defensive when you're reaching into his tub, so some days he makes it quite clear that he doesn't want to be messed with. Besides this defensiveness he sometimes shows, he's incredibly inquisitive and curious, not a bit as shy as my BP.

As far as tank size, I'm really not sure, because I'm going with tubs, which you may want to consider because of price and ease.