Yup, hopefully. Just remember, once you put them in there give them a few hours before adjusting because it will be wonky for a bit as the eggs come to temp and the air stabilizes back out.
No. Run it dry and see what your humidity is w/no water. If it stays abover 25%, preferably 30% ish run it dry and check the air cells. If not if you have a clean sponge wet that and put it in there or a cloth and see if that will get you about 30-35%. If you fill the channels I almost guarentee...
Did you buy the 9300??? If you did, don't trust the display read outs. Make sure you have your own checked thermometers. Chances are you'll have to set the bator higher than you need it to actually get it where you need it inside.
Oh, yeah, if the chicken is truely broody, she'll give you time. You can always buy the fake eggs to put in the nest if you are worried too.
Like Friday said, if they aren't washed and sitting in warm temps, they last longer. I believe we are one of the only places that actually refridgerate...
How many do you want to hatch out? Though if you don't have a broody, saving eggs is kind of pointless. Eggs viability after 10-14 days decreases significantly and there's no telling when a hen will go broody. I'd wait until she's actually broody and then collect your eggs. If she's a good size...