I am loving your thread
@Jesse1983, have been having some of those same questions myself.
As for my own experience: providing grass hay daily has really helped my does. I was 'just a pellet feeder' for 40 some years.

Now, as soon as the kits can get to it, they are sampling and supplementing from it also. Very smalltime (breed for my own meat) here but since I have put up those hay feeders I haven't lost a kit at weaning. I also do not recommend any alfalfa hay or alfalfa/mix, I want my bunz to get the full nutritional value included in their pellets. Many areas lack certain trace minerals in locally grown hay which the pelleted feed provides.
Hay = bunny popcorn! Yeah, unsalted, unbuttered popcorn but a good munchie between bites of dinner.

Protein content? I feed 18% to all, bucks and does. Size and breeding stages come into effect here... and only my bred or lactating does get Calf Manna, amount depending on stages of motherhood.
Good luck with your bunnies!