L1B ,cos to H1B 2013-14 in same company , if laid off before Oct 1 then ?

I’m on L1B for the current company [ expiring 2015 ]

Apllied for new H1B [ got in quota] as change of status [ starting oct 1 , 2013 expiring 2016 ] Have approval notice

What happens if i get laid off before oct 1 , 2013 Can i change companies with the approved h1b notice here ?

How long do i need to wait in the current company before i change to different company. [ as H!B transfer ]

Also how many days can i legally stay in usa if incase i get laid off { i mean how many days i have to look for job ]