Advice on GMAT Studies

Hello everyone,

I was wondering if anyone could give me some advice on my current GMAT studies. My profile and study structure until now are below and then my questions will just follow. Thanks.

Planned GMAT date: End of October/Early November (will make appointment soon)
Target Score: 650+

Have studied for two weeks with Kaplan GMAT Premier.
Took first Kaplan CAT Practice Test (530 36q/29v)
--However the whole Reading Comprehension section turned up blank so I missed 12 questions--

Question Breakdown:

PS: 14/22
DS: 8/15

SC: 6/16 (ouch )
CR: 11/13
RC: 0/12

Bought Kaplan Math/Verbal Workbooks. I plan on spending about 1.5-2 weeks on each, then to the Official Guides.
I know my weaknesses (SC & DS) and plan on focusing the majority of my efforts there.

Now for my questions.

1) I know the stereotype of Kaplan tests is that they greatly underestimate your score. However I have heard they have recently changed their tests and they are much easier now. Would it be reasonable to use this as a baseline score, or should I use up one of the free GMATPrep tests for a more accurate score?

2) It is recommended that you keep an error log of your practice tests and other questions. However, when I downloaded some of the templates off of this website, they seemed extremely complex. Especially when it came down to dividing the questions by which concepts they tested, as many questions test multiple concepts at the same time. Any advice?

3) Any other advice would be helpful

Thanks again.