I don't see that selling the second car will give you any boost to your FICOs. However, if you're getting a decent rate on the first car refi, and you don't need the second car, with the $5K negative equity your DTI will drop so that's a good move.
On CLIs, are you saying you've already tried on all your CCs within the last 90 days and gotten CLIs? With a median 710, I would think WAMU to be far more generous. I got $2K initially with around a 610, and DW got $4K initially with around a 650.
Any windfall cash to pay down CC debt, or were you planning to do that with the personal loan? I would still recommend you try a local CU. Rates will likely be far better that 25%.
NASA, Justice and Penfed FCUs are also very generous with their CCs. See the Friendly CC link in my sig. I'd take a shot for a NASA CC. $5K more CL CC will do wonders right now.