Nikaah & Marriage Issues

Delaying if a girl receives a good proposal

Q: I have questions for marriage of a girl 

1. If she does not like one proposal, does she have the right to say no to it? Or is it only the boys' family and her parents' decision? Likewise if she likes a proposal and after istikharaah her heart says yes but her parents say no, what's the ruling here? 

2. Let's say there is a good match. However, the girl's parents think that she is too young at the time, and also not mature enough. The boy is studying and it will take 2-3 years for him to complete studies for him and get a job. In this case if the two families think they're a good fit for each other what do the girl's side say? Yes, but not right now? Is that allowed? 

3. I heard (but I'm not sure about it) that there is a Hadeeth saying it is better when the proposal has been accepted that the boy should have one look at the girl. Two questions arise. One, is this hadeeth true (and can I please have the full hadeeth by word)? And two, is that what is only allowed? That the boy can take one look at the girl? Or (as I've also heard) the girl is also allowed to ask the boy to read one quranic verse? Does this have any relation to the mahr? 

Please explain to me in detail so I can understand. 

Husband not taking care of the needs and expenses of his wife and children

Q: I am a working woman and married. Both me and my husband are working in respectable jobs. I handle my own personal expenses from day one of marriage and have never asked for pocket money from my husband. 

I have two children aged 1 year and 1 month. My husband refuses to help in the my children's financial needs. Both of them are on formula milk and their combined expenditure is around 80000 which I am solely bearing along with my own expenses. 

My husband's income is more than me. He refuses to contribute even half. Alhamdulillah, I am managing but my question is what are the rights of such a husband/father over his wife and children if he refuses to contribute even 50 percent financially if he has more than enough money. What are the faraiz and instructions for the mother/wife in such a case who despite being married is living like a single mother?

Continuing a marriage if the mahr (dowry) has not been paid

Q: Is it permissible to continue a marriage if the mahr (dowry) has not been paid? 

I am currently married, but my husband has not yet paid the agreed-upon mahr (dowry). I would like to know if my marriage is still valid in Islam without the payment of mahr. What steps should be taken in such a situation? Is the marriage still considered valid, and what are the Islamic guidelines regarding mahr payments? Should I take any specific actions to address this issue?