H1B expired and willing to work in diff company with H1b

Hi , I have question regarding H1B , please help. I’ve got sponsored from company “A” in US and have my H1B from 2001-2004. ( first 3 years). From 2003 I went back home urgently and stayed here until now. Now Company “B” want to sponsor me, in US. How’s the process.can I extend my previous H1B,submit extention h1b with my given EAD number,my understanding I still have another 3 years (H1B good for 6 yrs) or do I have to apply from the begining? Where to apply, in US immigration office or in US Embassy here. My employer want me to start ASAP.do you think I can apply now on Oct 2012 with premium proses or the quote has been reached( not quite understand about it since when they start have quota for h1b?what should I do?

H1b Extention can be applied only if you are employed, otherwise you will have to go for a fresh H1. 2012 quota of 65K is over. You will have to wait till Oct 2013, apply for a fresh H1 in April 2013.

I though the proses will take 2-4 month,like my previous only took me 2 month to get it on 2001.
let say if I apply aprll 2013,it will take up to july, why I have to wait until oct 2013 to get my H1B and able to work?
If I want to expedite the proses with premium proses, will it be only 15 days working days?