Well, you have lots of time, so I think that's a good thing. Here's what I would do. Quant- You are doing pretty well already. Figure out what your weak areas are and attack them. Use the MGMAT guides to enhance your fundamentals and then take 10-12 GMATClub tests to bring you abilities to the next ...

I would do the MGMAT first. I would also advise you not to take 2 CATs per week. I think that's overkill. You would be better off spending that time studying the materials. I would take 4 total practice tests maximum. 2-3 should do the trick.

Take a few GMATClub math tests. If you can get used to the difficulty of those questions and understand why you missed the ones you did, you will definitely improve your quant score. Something to consider at least.

I would take maybe one more practice test. You don't want to overdo it and you will want to focus more of your attention on getting better. I would go for the Manhattan GMAT practice tests. Just take 1-2 of those. They are high quality.

I didn't use any prep course. I would recommend using the Powerscore CR Bible for critical reasoning and the Manhattan GMAT Sentence Correction Guide for sentence correction. I think the GMATClub tests will help you get to the 700+ level for math.

Definitely impressed by your attitude and perseverance. Congratulations.

I read some article somewhat recently that said the GMAC was going to focus less attention on idioms. I don't have a link to it, but I'm pretty sure idioms are less relevant now.

Thanks for writing such a full detailed debrief and congratulations on your score.