Q1 - The rain spiders should have some sort of mating display similar to that of T's, so when a male comes close to a female you should be able to see a different reaction than when pray is around.
Q2 - Rain spiders does not have the same length of lifespan than those of T's, so I would not be surprised if siblings mature and mate in nature. I don't think this would be a problem.
Q3 - I would follow the same approach, but I do think that you stand a better chance here that a male might become lunch during or after the mating.
My suggestion is that you shark tank the male with one of the females and see how she respond to him. Unfortunately I have not had the opportunity to mate these before, so maybe someone else can shed some more light on the subject.
SPIDER CLUB OF SA MEMBER
There are 10 kinds of people in the world. Those that understand binary and those that don't.