[Anypeny]

depends if you put it in the contract or not. If you stipulate it in the contract then the marriage is nullified if that condition is broken (same applies to anything)

Niqab is a valid difference of opinion though so i wouldnt divorce a sister because she chose a different opinion. her personality and zeal for islam and such like are far mor important

may Allah grant you a nice wife who makes you happy. ameen