1. start with I-140.
2. Yes.
3. depend on service center and case by case. Normally, you should expect 3-12 months for 140 results. 485 follows the time frame of other employment based cases. There has been a trend that USCIS will hold the 140 approval for 485 time frame.
4. AP and EAD can be applied. One concern is that F1 will lose student status once AP or EAD is used.
NIW全局的问题最好面对面咨询一个办过的人. MITBBS的移民版可以解决细节问题.