A:Answer I'd say it can be used in an apartment, taking some considerations into account.
It is heavy, but not more than typical stacked machines. It's comes assembled, so it's big to maneuver although you don't need to lift the dryer up onto the washer since it comes that way. It can be separated for installation purposes but must be put back together for it to operate.
It is designed to be vented to the outdoors. Certainly the gas dryer version must be vented outdoors, but I used a similar type electric dryer for years with a water filed "ventless" unit designed for dryers, which does add humidity indoors.