Law to Big4 - What am I qualified for?

I have an undergraduate degree in accounting, a JD and an LLM in tax.  I currently practice law at a small transactional law firm in the midwest (8 lawyers).  I have decided that I don't much care for the small town life and wish to relocate to an urban area.  The legal market in urban areas is ridiculously overcrowded these days and I think my best shot will be with Big 4.  My law practice was mostly estate planning and small/medium business transactions, with all of the relevant tax topics thrown in the mix.

I am considering taking the CPA exam and applying for a job with Big 4.  I would like to stay away from doing too much compliance (i.e. tax returns), although I understand it's rare to completely avoid this aspect.  I was hoping a few of you could shed some insight on the following questions:

1. How in demand are my credentials to Big 4 these days, provided I get the CPA?  Will I have the freedom to choose my location/tax specialty, or will I more or less need to take what I can get? 

2. I would very much like to work in advisory/consulting.  Do I have a good shot at this?

3. Is a CPA license even worth getting at this point?

4. What sort of salary/position could I reasonably expect if I was hired by Big 4 at this point?  This is an important point, as I do have student loans.

5. What sort of tax specialty would my educational background prove most useful for? 

6.  I am 27 years old as of the date of this post.  Is this kind of lateral move common at all?

Thanks in advance, any insight is much appreciated.