Absolutely FANTASTIC hatch rate! Wahooo!
Not true. I am one of the folks who has never, ever, moved a setting hen from her chosen nest. I do mark the eggs, though, so I can remove any "added" eggs laid in the nest by other hens, which they will do. Silly girls.
Yup, your hen will take care of that process; you may notice her in a sort of trance whilst she's on the eggs. The last few days, as she hears/feels/senses chick movement, she sits even more tightly and may not get up to eat or void. Or she might, but her time off the nest will be much shorter.
Mine hatched 1/1/11 (part of one of the Mahonri's Annual New Year's Day Hatch-a-thon (here on BYC) and I still have a Josie left from the four (one cockerel and 3 pullets) hatched from my Trader Joe's eggs. Two of the hens went to other folks when I had to get rid of some roosters and gave them away with a hen apiece. TJ the rooster died protecting the flock (he was one of several roosters of all different breeds) but lordy, was he a gorgeous rooster! The 3 Josies are exceptional layers - all White Leghorns.