~ Most boas are very docile, all of my three Colombians (spelled with a "o" BTW) are very well mannered and have never struck or bit me. Start with a baby and grow with it, babies aren't intimidating at all.

~ A male Colombian *should be just fine in a 4' vivarium, and it actuality it doesn't take up that much space. My male (a little over 6' last time measured) fits fine so far in a 4' vivarium. Most Colombian males stay between 5-6' with both smaller and larger exceptions.

~ Adults can be fed every 2 weeks and babies every 7 days. Not that expensive to feed, especially if you buy f/t in bulk.

Here's two older pics of my male Colombian (he's grown a bit since these were taken) but you can see he's not huge (he was a little over 2 years old in this pic and big for his age IMO). They're not hard snakes to handle, and if starting with a baby your family can learn to handle it as it grows into a sub-adult/adult: