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.