1.Her box is about 3 ft from the coop floor bedding. Other hens seem to be trying to use the nest. Should I move her? How and when? Will this make reintegration difficult? I have an unused rabbit hutch I could put her in if that would be good.
You must mark any eggs under her so you can remove any eggs other hens volunteer to the nest.
I like to separate a hen to preclude volunteered eggs and any conflicts.
A hen can hatch in an elevated nest and the chicks can get out of it with no injuries but they probably won't be able to get back in. I usually put broody hens in their own building, provide food, water and space and forget about them for 3 weeks.
2. If she hatches any chicks, will they be safe with her and all the other birds(8 hens and a roo)? I have a brooder if I need it. What preparations should I be making, for her and myself?
They will be safe. In the wild, hens keep secret nests and then introduce the chicks to the flock. The broody hen is a formidable foe and will protect her charges with her life against all comers. By the time the chicks are weaned, they are accepted as members of the flock.
3.At what point, if any, should I worry she's not taking care of herself? Is it likely she has left it a couple times and i just haven't seen her? Ias this a baseless worry, she has it covered(pun intended lol).
Never worry about that. As I said, hens have been hatching eggs for millions of years without comitting suicide by not eating, drinking or crapping.