The problem with gun smithing is that you need to either be able to get the barrel into the head stock, or get it between centers. I would make this my first priority, you must be able to get a barrel mounted in the lathe somehow.
The QC gear box is a big deal for me. If I have to change gears between rough and finish cuts, I will avoid doing one or the other.
As for moving it, you would be amazed what can be moved. Unless your basement stairs make a sharp turn, there should be no issue getting a heavy machine down there. Even then, the lathe can be stood on its end and taken down that way.
In general, "lifting equipment" like cranes are not used, just dollies, pry bars, and come-alongs. A foldable engine hoist is a good idea for getting the machine onto the base.
Do not cringe away from doing things like drilling through a wall to the other side to make a drag line anchor - just patch and paint when done, no harm will come to your house doing this. If your basement stairs have a tight turn, consider just removing them and lowering the machine with a winch. Around here, most basements are almost after thoughts, and the stairs are just nailed at the top and bottom. They can be removed and replaced pretty easily. Lastly, you can rent a buddy with a back hoe and dig a walk out. You can justify this by saying that it will help keep metal chips from migrating from the basement shop to the living area (it can be a real issue with home shops).
In my experience, wives tend to get fussy about stuff like this. Priorities are important. I found getting rid of the wife gave me some extra space to store my guns, and I can buy all the machines I can afford