Congrats, they are awesome. I just found some new Cristobal froglets yesterday in a viv that contained a pair that I was sure included a female! Awesome surprise. When one of those little guys pops out, it sure makes all the work worhwhile.
Regarding how many springs to feed. I'm relatively new to pumilio (since last summer), and I've been told to put some springs in every day and not rely entirely on the springs reproducing in the viv. If you have enough to add a decent amount each day, the adults will pick off the extra.
I found that it's best to put ffs in first to keep the adults from getting too many of the springs. I also try to pour the springs down along the glass or in a corner to get them into the leaf litter. If they linger on top, the adults will pick them off pretty quickly and few will survive to reproduce.