Casting Material

Platinum silicone is going to give you excellent results on the molds. I would recommend degasing or pressuizing.
As far as casting, either urethane resin or casting epoxy should work well. Again, degas or pressurize for best results.
Smoothon makes great products, but they've gotten pricey in the past year.

 

rebound 25 , just put a print coat on first no need to de gas then build it up if your not making a bunch of them just use foam or Bondo for the mother mold

 

Rebound 25 is great stuff. You definitely don't have to Degas yeah, but even dong a thin seal layer it is still possible to get micro-bubbling, which can transfer to a cast as little "bb's" or a faint "foamy" texture. It's easy stuff to remove/deal with but considering that silicone even picks up finger prints I personally still Degas just to make sure that first layer is perfect with whatever texture is there. I've even run into the same thing with their Moldmax 14 non vacuuming.