Should I have a specific career in mind before applying?

Hi Guys,

Sorry for the lengthy rant, but I’m in kind of a rut and want to figure out what I should do.
I’m not too crazy about my current job path (CPA, Financial Reporting at a large insurance company). It doesn’t have much future and offers minimal job transferable skills. I know I want to change jobs and job function but I don’t know to what. But if I’m looking to change functions, I know an MBA can help. I could stay at my current job and safely coast to an above average salary and space out for the next 40 years, but that’s not too appealing.
So I’d ask the following:

  1. Should one pursue an MBA if they're not sure what they want to do with it? Is it wise to walk into an MBA program thinking "Well, I don't know what I want, but maybe I'll think of something after going here. " Should one have a definite career plan before applying? Am I'm better off taking the risk and going than to not go at all?
  2. Is it even worth it if you can't make it into a top school?
  3. My credentials are as follows: GMAT 600 to 640 to 650 and a 3.0 GPA. Not great. If I can't get my GMAT up should I switch to the GRE? At some point, does it look bad if I take the GMAT too many times? Is there any way to make up for a sub par GPA like mine? (taking community college classes?)
  4. I live in Southern California, a Pepperdine Recruiter threw a $40 K scholarship my direction to attend their Fully Employed Program. It's a small school but my investment would only be about $25k due to the scholarship. It's not going to get me into many interviews by virtue of its name so I may be throwing that money away. People from smaller lesser known schools have to work harder to make their opportunities. If I'm willing to work 10 times harder at a smaller school to get those opportunities, would I make the price of admission worth it?
  5. What would my chances be of getting into USC's full time program. Just at thought, but if I really want to switch functions, a full time program may help a lot.