Sheka, I'd either geld your colt right now, or board him away somewhere that is experienced with Arab studs.
I used to help out at a Polish Arabian breeding farm and Arab studs are hot to handle. I have yet to meet a nice placid Arab stud.
I helped out with many breedings and got to see a birth before. Now, the mares that were bred weren't maiden - so the birthing was fairly easy and quick for them. I haven't heard of birthing complications though and I would never even want to think about putting my mare through that. She is still young, I'd worry more about her training and such as of right now.
Do not pasture them together, I'm not sure your situation though as regards to pasturing/boarding.
There are SOO many Arabs out right now, so unless your horses are papered, I wouldn't bother.
Unless she has impecable comformation, personality and trainability.
If she is registered, i'd take her to a few Arab shows and get some points on her.
pics?