Questions related to an offer

I am currently a Ph.D. student in chemical engineering and expect to get my degree in May 2008. I already got my mater's degree in August 2007. Recently, I received a job offer. It is a process design engineer position. I had some work experience in China, but not highly related to this position. They offered 72K a year and I accepted it without negotiation cause this will be my first job in US. From the job deion on their website, it requires bachelor's or master's degree.

I have some questions here:

1 In the offer letter, it says Position of Process Engineer (Engineer I), an Exempt Position. What does the "exempt position" mean?

2 My plan is to apply for both H1B and OPT and start my work in May 2008.
I will use my master's degree for the H1B application. Because this position does not require a Ph.D., if I apply for OPT based on the doctorate degree (I will probably send the application out in late January 2008), will the OPT application hurt my H1B application?

3 Even without the application for OPT, if they know that I am currently a Ph.D. student, will I have problems to get H1B?

If there are problems with my plan, are they any solutions? Thank you very much for any inputs.