I agree with @Ungoliant that the risk probably is minimal with proper care, but having a small baby is stressful enough in itself and if this is something that you´re going to be worried about it might be better to sell your Ts. You can always get some again at a later time.
Typically the seller will provide you information regarding the size of either its diagonal leg span or its body length. The growth rate of tarantulas varies between individual specimens and things like feeding schedule and temperatures also comes into play.
My wild guess is that it ought to be...
Yes, everyone is reusing their enclosures. If it isn´t that dirty you might just use water, but I usually give it a scrub with dishwashing soap. As long as you rinse it off well there shouldn´t be any issues with that.