H-1B Visa

I am in a very difficult/complex situation, the situation is as below:<br>
Have been on H-1 for 3 + 3 + 3 + 1 years (last 4 years extended based on approved I140). Have approved I-140 with priority date of June 2010 in EB-2 category. H-1 extension was denied last year hence had to leave employer A, now I am on H-4 and will be soon filing H-1 with employer B. I have following questions on which I am requesting your opinion. <br><br>

Q1. When my priority date becomes current and if I am still with employer B, can employer A still file my I-485 and that way I can then get the EAD and join him on EAD? :<br>
Q2. Further, do I have to be working with employer A on an active H-1 visa to be eligible to file EAD when my priority date becomes current? :<br>
Q3. If question 1 approach works, can I then continue to work with employer B and employer A can process my green card in parallel. :<br>
Q4. What are the risks in working for employer B when my I140 is with employer A. Note that employer A is willing to preserve my I-140 and process green card eventually without me working for him, because he is unable to find me any projects? :<br>
Q5. I do plan to file for a new GC with employer B but worry is the priority date is likely to become current before I complete GC process with B. :<br>
Q6. Do I need to be with employer A for my wife to apply H-4 EAD based on my I-140 with A (note that currently I am with employer B).

I am an Indian and have been living in London for the last 6 years and currently in the process of getting British Citizenship, which I am hoping to get by April and subsequently British Passport by June. I work for a leading international bank in London.<br>

My girlfriend is currently doing Masters in Illinois, USA, so, I am looking to move to US, but understand the H-1B visa is a bit complicated.
<br>
My question is, how does the quota system work for H-1-B visa and when does the new quota start, and what's the best period to apply for one? So, If I am looking to move there in October 2015, when do I have to get an employer to apply for H-1B for me (provided an employer agrees to sponsor me)? or, is there a particularly good time to apply for H-1B visa?
<br>
Also, is it easier to get the visa if I am there physically in the US or it doesn't matter?

I got my H-1B petition approved in 2008 and again got it extended in 2008 unto Jan 2011. Now, I have never used both these visa's to work in US. Though, I have traveled few times to US but on B-1 visa for meetings with customer. Today, one of my friend told me that I am eligible for cap exempt H-1B application if I get job in US. Also, what will be the processing time for this cap exempt H-1B. Can this be done in premium processing in 15 days ?