Well, of course a chicken can hatch eggs and raise chicks. How do you think it happened before incubators were invented?
I've used black sharpies to mark my eggs for years. They won't hurt a thing. They don't rub off like pencil does.
If you have an area she can be isolated from the other birds, then you won't have new eggs to remove all the time, but I'd mark them anyway. That way if something happens and other hens get in with her somehow, you'll know which eggs are the ones she's been sitting on. Accidents happen.
She needs to be able to comfortably cover all the eggs with her body, so as long as she doesn't have too many, it should be fine.
Make sure you give her eggs with good, strong shells, (I candle mine before setting them under a hen, and that shows all kinds of thin spots and weak lines that you can't see under normal light, the light shows through brighter in those spots) to reduce the chance of eggs breaking in the nest. I check under mine daily, both for new eggs that I need to remove, and to clean up if an egg got broken. In that case, I just take out all the eggs, (set momma on the floor for a few minutes, maybe she'll decide its a good time for her daily meal break) scoop out the wet, icky bedding, replace with clean bedding, see if the remaining eggs need to be wiped off, put them back, let mom back on the nest. I've even washed goo-covered eggs, put them back, and had them hatch just fine. Just work fast, so the eggs don't get too cold for too long. They can tolerate some cooling, so don't panic.
It helps to have a nursery area for new babies and moms to start out, but plenty of folks just let them hatch in with the flock, and most momma hens are pretty good at protecting chicks once they hatch. I do both, because I usually end up with more broodies than I have private spaces for. I have the nursery reserved for a couple of broodies who are gonna hatch me out some turkey eggs, soon. There are young Delaware chicks in there right now, but I've sometimes kept young chicks and broodies together, and it works out ok, as long as you can move out the older chicks by the time the eggs are ready to hatch.
I hope this is helpful, good luck with your hatch! Salmon Faverolle/Black Jersey Giant, that'll be an interesting mix! I bet they'll be beautiful. Post pics when they hatch!