they will run 9spd (and even 10spd with road shifters)
30t? Depends on the cage length but I think they are ok, I run an XT body with a 600 road mech cage and that does 30t but theres lots of chain to flap around if you dont get it right
using a 9spd chain helps as the ever so slightly narrower chain can help with the chain line
when you fit the mech, adjust as if it were a 7spd cassette, it will then shift just as well