I think u should be all right.
F-1 is not dual intent (your sole intention is to aquire knowledge and return) as H-1 so going from H-1 to F-1 while under EB2 process might not be possible, since you have shown your interest to stay in US by applying for EB2. However, going from F-1 to H-1 which is a dual intent SHOULD NOT be a problem.
Unless a legal expert comes here and responds to these questions, I strongly advise other posters to also consult an immigration lawyer (we have so many Nepali lawyers now) and maybe post on immigration forums that are rampant nowadays. Immigration issue is a serious one and you can't rely on these kinds of info sharing places to make such a huge decision.
