You probably haven't seen any responses yet because not everyone checks this thread regularly and your question is VERY broad. Most of us have logged hours trying to figure out this stuff for ourselves and are aware of all the contingencies that crop up--so it would take quite some time to dig into your situation to answer you question properly.
However, it'll only take a few minutes to throw a few things out there to save you a little time in the process, so here goes:
For starters, obtain all the relevant Excelsior reading material. You need the catalog for your area of study (I believe it would be the Business catalog) and there's a Guide to Credit by Examination that is essential to mapping out your plan. Both are available on the Excelsior site. To answer your first question, the quickest and most efficient way to complete your degree, in my opinion, is testing out of as much as possible. I cannot really recommend which tests to take, other than the obvious, because I don't know which tests will duplicate what you already have.
I initially planned an associates degree along the way, but decided against it as I didn't see the value in spending the extra money.
General Education Component
I would take the CLEP Macro and Microeconomics exams for those requirements and, assuming they don't cover the 6 social science credits you still need (they may--you'll have to ask), you can take any two of the four psych related CLEPS (Sociology, Psych, Ed Psych, HG&D) for those. If you want a GPA, you should always look at DSST tests first, though, since they are graded by EC and CLEPS are pass/fail. DSST has a Statistics exam for that requirement. The rest you can fill in with tests that you like from that category in your Guide to Credit by Examination. DSST Criminal Justice is very doable--even though it's tough to score high it should be easy to pass.
Info Lit you can do at a local community college for cheap (see the link in my signature below) or Penn Foster, I believe, has an on-line option, or, if you have the money, it can be completed through EC very quickly. Some have done it within a day or two--but it's around $300.
You'll have to go somewhere for Accounting--at least Managerial. CLEP still has a Financial accounting exam. Again, Penn Foster probably has something. My local community college had two 5 credit courses that satisfied the Financial and Managerial Accounting requirements which, while difficult, were cheap ($20 per unit in California) and satisfied the requirement and gave me ten units.
Business Law and Marketing are CLEPs and you're going to have to go out and find those other Marketing classes you need unless Excelsior or Thomas Edison have tests for them.
It's easy to find lower level alternatives and more challenging and expensive to find upper level alternatives, so I would advise you to take upper level whenever it will help satisfy your upper level requirement, whatever that is. It could be all in Marketing.
I would strongly suggest that you take EC exams for Organizational Behavior (I'm studying for that one now) and Ethics. In fact the DSST Ethics exam does not duplicate the upper level EC exam, so, if you need it, you should take both. You can study for both at the same time (I even took them on the same day) and you kind of get a two for one. The lower level DSST will count as Arts and Sciences credit. Org Behavior and Ethics EC exams will fulfill the requirements AND count towards the number of upper level credits you need.
So, again, to be clear, these are just ideas based on my experience and LIMITED knowledge of your circumstance. ALWAYS have your plan verified by a counselor. Email works great. I've been enrolled for a year and have consistently received prompt responses. If you send them a broad question, it'll likely take longer. I usually made mine very specific.
Finally, here's a
link to my plan for a general business bachelors degree through EC. I've completed Acctg, Macro, Micro and ECE Human Resource Management since I last updated this, but it'll give you an idea of how I put my plan together.
If I were you, I'd sign up for InstantCert (if you haven't already) and start studying for some of the REQUIRED exams NOW. As in, RIGHT NOW. There's no reason to delay. The beauty of InstantCert is that EVERYTHING is available as soon as you register so you can just pick and choose and, most importantly, START.
Good luck and have fun!