Hmm... No idea whats the spacing in the rear end for that bike, my best guess is that you bike is spaced 126mm... the new wheels no matter how many speed you can put in there (8.9 and 10)... those wheels are 130 mm in the back.

You can do something called cold setting or just use the wheels forcing the frame a tiny bit so the wheels fit in your bike, you bike is made of steel and you shouldnt have a single problem doing that.

No idea if your cassette will win in the wheel, shimano is not super consistant with spinelines, im not a shimano person ok? so I really dont know if the spineline of a 7 speed will fit the 8/9/10 speed one. As for the spacers you are asking about, yes you can put them, as long as the cassette is tight shouldnt be a problem.

Hope this helps.