I believe her eggs will be fertile for 2 wks? Not quite sure about the specifics on that one.
Do NOT place fertile eggs in the fridge! It kills them! If you're gathering eggs to put under a broody, simply leave them on the counter in a spot that is as draft free and sunshine free as possible (I put ours in a cabinet in a bowl). Do not collect more than 8 days worth, then the eggs start to deteriorate in quality. Personally, I did 4 eggs - enough to up the odds of pullets, not so many that I couldn't deal with 'em.
The eggs will start to form as soon as heat is applied to them, so if you'd like them all to hatch at the same time, collect, store on counter, put under broody at same time. If the eggs are staggered (1 today, 2 tomorrow, 1 the next day), so will the hatch. Challenging for a new Mom to deal with. Not impossible, but more challenging.
I have straw bedding in our nestboxes. The pine shavings are too dry and easy to get mashed as Mom moves about and re-makes her nest. I did have to add more straw as she went along. Yes, I simply tucked it in next to her and she figured it all out. Good chicken Mom!
We're all here to learn, to share and to enjoy our chickens.....wonderful, isn't it?!