I love columbians, I prefer them to brazilian both in look and temperature. My female was about 7 foot and pretty chunky (ate rabbits!) but dog-tame. I think they will tame down quite a lot if you put in the time and effort, 2 foot there's still time. My male was only half that size though, about 4.5 foot but still very tame, placid, easily handleable and they always fed no problem.
Babies always strike like crazy but I always found brazilian worse than columbian for that and a lil bit of time and patience will prevail.
I don't know anything about a rack, I kept my pair in a 5x2x2 viv and fully grown they need a fair bit of space especially if it's a chunky female.. but at 2 foot you're probably okay for space. I've read in places that they need branches to climb on, mine never climbed anything, but did like a nice basking spot.
They do need a pretty constant high level of humidity which might be a problem in a rack. Mine also used to soak in a large tray of water every day and I would try and supply something large enough to soak in as well as drink from, and spray daily.