بسم الله الرحمن الرحيم
(1) Yes, in this case ghusl shall be wajib on you provided you remember the dream.
(2) There is no need of doing ghusl again, only the impure place should be washed. However, fresh wudhu shall be required provided the impure water flows out of its place.
Allah knows Best!
Darul Uloom Deoband