I doubt they will pill, so you should be good there.
I like to wear cardigans unbuttoned and found they didn't work well for that. If you wear them buttoned they'll probably work out a little better.
This one, jet?
If so, I'd buy it from you—unless that 22" chest measurement is wildly inaccurate or something.
Are the sweatpants tapered?
Are the sweatpants tapered or at least slim?