baby bci's are anywhere from a foot long to about 16 inches. there is a chance your bci could reach 12 feet, but that is probably given the fact that it was power-fed, and is a female. an average female would be around 8 or 9 feet long, and a male probably 6 or 7 feet. bci's, if kept correctly, are easy to handle. they are considered by many to be a "beginner's snake" just like a bp. a little personal experience piece of info... i've had my bci about 3 weeks, and at first i was a little nervous around him... but i already feel confident everytime i go to get him out of his enclosure. he's just a goofy snake.
hope i helped.