Almost always, one eye is affected more severely than the other. You may have double vision in the affected eye. You won't go completely blind from cataracts, because some light always gets through. But vision gets more and more blurry as cataracts progress. To restore clear vision, yes.
Cataract surgery is very common, and in the vast majority of people, it's very successful.
It's usually done in the ophthalmologist's office using local anesthesia. The operation only takes about an hour, and then you can go home. Sometimes an implant is not appropriate and a contact lens is recommended instead. Afterwards, you'll probably be given eyedrops to use, and you'll be told to avoid vigorous activity for a while. Complete healing often takes a few weeks, but most people see things more clearly right away.