Red Taled boa, I'm a new owner, ?'s...

[e burna]

I got 2 sisters. They are around a year old. around 39 inches. I fed them each a rat and 2 mice, which I'm told I should have stuck to one or the other, why? Also, I want to get rid of 1 and just keep 1 (got them both from same person as a deal), how hard will it be to get rid of one, and what can I expect to get out of it $$ wise? I was also told I can feed every week, or every 3 months? Which is it? I don't want them getting too big too quick(which is what I was told will happen if I feed every week), but I also want them to be tame so when I handle they will not strike me out of hunger. Sorry for so many questions, I'm sure I will have more, but that's all for now. Thanks for reading, and hope someone can help me.