questions for H1 transfer

I am holding H-1B visa in University which will expire at the end of next year, but I have to change my job soon as my financial support will end very soon. Now I got an offer from another university. So I need to file an H-1B petition to work there. As I know, since I am currently since you currently hold H-1B status you can begin
the new work once my petition is filed and receive the receipt notice from USCIS. But I have several questions to ask.

1. When I file my petition for new H-1B, do I have to file the new H-4 for my wife? My wife’s current H-4 visa will not expire until the end of 2005. If I change my H-1B, I do not know if my wife has to get her visa changed with my case since she is regarded as my dependent. For example, if my new H-1B visa is only one year, it will be better for her to keep her currently one. If legally she could keep the current one, could she change it whenever we feel necessary as long as I am still in H-1B status?

2. I heard that it will take approximately 6 months to obtain the approval from the Immigration Service when a petition for H-1B is filed (not a premium one). Before I get the final approved H-1B visa, could I start a new H-1B petition if I get another offer and decide to change it? Does anyone have the same experience? If I file this petition for myself and my wife (H-4), could she start the change of her H-4 to F-1 before she receives the new official H-4 from USCIS?
Thanks a lot