Greybear, My sportsman was set on 100.5 when I got it and I have never changed it. I tend to get early pipping. Most of mine that are gonna hatch usually do so on day 20.
Does yours have a bucket on top? Some do some don't.
Yes you have to keep the tray inside filled either with the auto feed from the bucket or manually by you.
I keep one of the vents in the back slightly open.
Mine is not insdie so I haven't worried with a filter but that would make sense.