re: Are the US/Russian systems alike?
There's an airlock for the US spacesuits and another one for the Russian spacesuits.
The Russian spacesuits can fit on most astronauts, provided they take their time to sew the spacesuit (threads would shorten the sleeves or the legs). The Orlan spacesuit can be accessed from the back and a "door" can be shut (with in the back, the life support system). It's one piece with a hatch behind.
I don't know how long Orlans can stay in space aboard a space station, but it could be years.
And the Orlans don't require a reduced atmospheric pressure.