Trogdor, welcome to the forum.
If your keet gets lose and you have to catch him, one way is to put a hand towel over him, then you can hold him without getting bit or having to squeeze him.
If you leave him in the cage until he gets used to his environment, if he gets out he will be quite willing to go back to his cage if you just wait on it.
It sounds like your original keet gets to come out of his cage, but will go back in on his own. The same thing will happen with your new keet once he considers the new cage home.
A good webside to determine sex and age of you keet is:http://www.budgieplace.com/
Good luck with you new addition. Let us know how it is going.