My ratio is 3 DWF for 1 RNG and my trade partner just got Pinsir, so I no longer need it. If you have anything else not on my list...you can replace it.
It's hard to say. It really depends on what is requested. My trade partner works on the parents for me and I RNG the request. Average time is probably 2-3 weeks. Depending on what is going on outside of serebii.