We put in a concrete hangar floor and the finish is less than
desirable. There are patches where it's recessed (about 1/8"- 1/4"
recessed and rough) and then other areas where it's rough and proud
(about 1/8") with swirl marks.

Is there anything we can do to mechanically smooth this? Do they make
a big sander for concrete and how well does it work?

Is there anything we can do about the low spots or do we just knock off
the high spots and then not do anything about the low spots?

This is a new hangar floor (a couple months old) that hasn't had any
oils, etc on it yet.

We were hoping to level/smooth it pretty nice and then put some sort of
paint or sealer on it so that we could use a dust mop instead of a
broom . Recommendations on the best smooth sealer for the money
(knowing that it's a new floor and won't have oils, etc in it yet)?