So if she wants to go to school on fall what she has to do? she has to apply for COS and I believe she won't be able to make it for fall.

if she wants to go to school on dpring 2010 what she has to do? she has to again apply for COS

Since still she is in OPT right now, does she has to apply for change of status if she joins the school for this fall or if the college issues I20 before OCtober 1st, does she need to apply for COS? till Oct 1st she is still in F1 but on Oct 1st she will be automatically in H1B. Getting I20 doesn't matter. Anybody can get either in H1/H4/J1/J2/B1/B2 etc but what it matters is when INS approves your I20 (or COS) then you will be in your designated status.

Is it necessary for her comapny to ask USCIS to cancel her H1b? you can do by yourself but it is better if your company does it.

If so how long will it take? it depends. anywhere from 1 month to 4 months.

During that period, can she attend the college? during that period which means....she will be in H1.....H1 can attend college anytime they want.

What is the chance of rejecting the cancellation of H1b if applied before Oct. 1st. time is preety bad these days. nobody can predict what will happen next. If properly applied with good attorney....it seems there is less chance of denial at your case.

Waiting for your resposes. these all judgement are based on my old experience. please wait for more respose or consult good attorney without wasting time.

Thank you in Advnce. np