Need to travel outside US before H1B effective date, which Visa to apply?

[louise007]

I graduated in May 2012. My OPT will expire in July 2013. My employer filed my H1B petition this month (April 2013) and is approved by USCIS. Can I do business travel outside US and come back in June 2013? My F1 visa stamp on passport was expired. So I have to go to US embassy in the country I travel to apply for a new visa stamp in June 2013. But H1B will only be effective in Oct 2013.

Shall I still apply for F1 visa stamp?

Is it true that once my H1B petition is approved, my visa status will automatically changed to H1B, if I apply for F1 visa (still in the effective period of my OPT/EAD), the action will be considered abandonment of my h1b which is already approved? Then will result the cancellation of H1B?

THANKS!!!