Most Shi'i scholars consider it necessary to remove nail polish for wudu'. (This is apart from the view of the late Ayatollah Fadlallah, who did not consider it necessary to remove it for wudu'.)

However, regarding feet: In Shi'i fiqh, for wiping the feet in wudu, it is necessary to wipe from the tip of one toe to the ankle. If one toe does not have polish (such as the little toe), one can do the wiping including that toe, and fulfill the requirements of wudu. However, that does not work for ghusl, since you need to wash everything. 

Hands: The above doesn't work for hands.