H1B to F-1 and to H1B on graduation

1. I had an H1 filed in 2000 by a company in US and I worked with them for 5 mnths before being laid off. I went and joined a MS course in 08/2000 and got my H1 cancelled and new F1 issued.I had an OPT issued during my MS in 2002. However, I left the next day I graduated in 12/2002.So essentially i did not use my OPT though it was issued.
I came to Us again in 2005 and my first cycle expired in 06/2008 and extended to 2011. I am going to B-school in 08/2008 and I believe that I am not eligible for another OPT since already used one during masters?

2. Have H1b- cycle 1 expired in June 2008, extended to May 2011. Now, I am planning on changing my status to F1 and continue education in an accelerated MBA course. Since I will not have OPT eligibility after graduation, can I ask my potential employer to request a change in status to H1 without reapplying for a new H1 through the cap/lottery? Would this mean that I fall outside the preview of lottery and cap and use the remaining time on my current H1(cycle 2)??

3. If i need to travel internationally as part of course work, I understand that i need to get a new visa stamping in the country that I am travelling to. Does that mean that my H1 b visa on passport will be invalidated without prejudice and I cannot use my cycle 2 H1B visa(mentioned above)? Will I have to get a new H1B petition filed on graduation and go through the lottery?