I thought you decided after lots of research? Seems like those are the things I would be researching before I ended up with a 20' anaconda I had know way to care for...
Anyway...enough flaming...
"red-tails" tend to be very docile, anyway, but you shuold notice that it willl gradually get more and more comfortable with your handling it...
There are at least two kinds of "red-tails" that I know of. Boa C. Constrictor, and C. Imperator. It seems that at least in the states, C. Imperator is more prevalent, but I don't have numbers to back that up.
They vary in size, but from my reading, I'd say you can expect it to be between 6' and 8' as an adult. The females tend to be larger than the males...As for how long it takes, it depends on the snake, the environment, its sex, and feeding schedule..I have sen them 6' and a few inches thick at 3 yrs old. Mine is about 15-16 months old and is ~40 inches long, with a 4" cirumference.
Basically, you need moderate humidity, a basking spot,a hide space, and clean water. You will want to light it during the day, and keep it dark at night. (You can get black bulbs...)The temperature should be aroun 90-100 in the day, and in the low 80s at night. Various sources will tell you slightly different numbers. Keep all sources of heat shielded, cuz it will burn itself.You need a tank with a lid that latches, and cannot be bent iopen. My snake spent the first week looking for ways to get out...
I have never bred snakes so I can't help you there, but I think you need tom cycle the temperatures and day/night cycles to simulate the various seasons...
I have attached some links...
Good luck!
http://www.kingsnake.com/smhs/redtailcare.html
http://www.redtailboas.com/general_care/general_care.html