If you want to learn how to probe, it is an OK thing to learn. Aint a bad idea to learn on some DOR if you have the chance, or have a qualified person show ya. You should be able to tell just by looking what your king is though, as most colubrids are to darn easy to tell by looking.
As for the milking, I only see that as nessesary if your working in labratory environment or in some research/conservation study. No need to dose yourself with venom to build up immunities, especially as it seems your not all that experienced in keeping hots. Frankly only a few folks do it, and they still have physical problems from it. They are as well folks that are around MANY venomous snakes a day, and only do it out of their own thoeries on venom. Seriously it just seems silly you would want to follow that route. If your planning on keeping hots, I would push the idea of safety and experience over what you seem to think it is all about.