The Limited 1 gacha has increased chance to pull some new girls which are all piercing. Limited 2 gacha has increased chance to get slice girls. It depends on which type you are looking for, if you need slice go for limited 2 (if your 5* is orchid you probably don't need this one though.) if you want one of the new piercing girls go for limited 1. If you absolutely don't care about either you can go for the premium gacha I suppose.

Not sure about the level 30 quest but it should be reasonably easy.