Woman seeking employment outside the home

Q:

1. Under what conditions can a married woman seek employment outside the home?

2. If a woman does work, what rights does her husband have over how she spends her money? What rights does a wife have over how her husband spends his money?

3. Please confirm what are specific things that a man is required to spend on with regards to his wife that fulfills the decrees of Quraan, Sunnah, Shariah etc.

Jokingly getting married

Q: Does a nikah done as a joke (just for the sake of fun) in a friends gathering without the presence of the wali, become valid?

Is it valid when the girl says yes just because of peer pressure of acceptance in a group and without having the knowledge of the sensitivity of this subject/issue of nikah.