My H1B status started in Nov’06 and I was on H-1B until Nov.30’09. I applied for COS: H-1B to f-1 for spring 2010 and USCIS approved the case. One of the employer's in the U.S. is now willing to offer me a full-time job and I am planning to file for COS: f1 to H-1B.

Note:
1.)I have a Master's in Civil Engineering.
2.)Currently pursuing - MS in Computer science
3.)Employer Willing to offer full-time is a company related to Civil Engg. field
4.)My previous work experience while on H-1B (Nov'06 thru Nov'09) is in Civil Engineering field.

Q-1: Please let me know the best applicable procedure to apply for COS.
Q-2: Will there be any conflict of areas of interest related to my previous work experience,current f-1 status Vs. new employer being in Civil Engineering field.

Thanks