The guys that are telling you to disassemble it, are on the money.
The machine will break down into manageable lumps, easy enough for two guys to get up a flight of stairs with on a furniture/appliance dolly.
Get a dolly with a strap that ratchets tight. Rent one from a moving supplies place if you gotta.
Remove the head (easy, straight off the top of the column), remove the table (some fiddly bits, but not rocket surgery) then the base assy of the mill with the column intact is a two person lift.
Don't try to carry this stuff up a set of stairs, eh. Your backs don't need it, and you only gotta drop on piece to hurt someone badly. Not to mention damage to the house, or the machine.
The sheet metal base should be last on the truck = first off. Assemble in reverse of the breakdown.
Got a dial indicator in the lot?
When you get the machine in place, post and say so, and you can get a bunch of info on setting the whole unit square and straight. Or search the term"Tramming a milling machine" on Google or youtube, to see what the drill is.
You might be lucky and have the mill be fairly straight, or you may need to shim the column a bit or a lot to get your alignment. Those are worries for later.
As much fun as it is to chase a bubble back and forth on a precision level, you don't need one bad enough to buy one. Having the head square to the table counts, having it square to the planet, well, that makes the coolant drain better, eh. If you can get both, great, but the money a good precision level costs (and the surface plate to calibrate it upon) is money better spent on tools you will use often. Borrow a level, if you can, and you feel the need. Otherwise, level it as well as you can with a carpenters level, and then square the head up, and it's good to go.
Try to keep in mind that you are not making parts for NASA here. Square and level withing a couple tenths is not as important as it is to someone that is. Withing a couple thou is going to be really good. Closer if you want to obsess, but if you are that hung up on it, you'll never be happy without spending the price of a house on a mill.
Village Press. Look for the mention of Mill-Drill adventures. Lots of great info there!
Cheers
Trev