Retaking GMAT - HELP with study plan!

Hello All,

Pretty new to the forum but have been hovering around the threads for about 3 weeks now.

A quick recap about my GMAT journey so far:
~~~Signed up for GMAT exam to be taken on the 27th of Sept~~~
- Jul 24th: GMATPrep CAT (1) - 530 (Q34, V28)
Went into this pretty blindly, just read up on the intro about GMAT and what type of questions one can expect to receive. I took the CAT as a diagnostic test to pinpoint my weaknesses and start my studying
- Aug 7th: GMATPrep CAT (2) - 640 (Q42, V37)
Was pleasantly surprised by this 110 point improvement, especially since my verbal went up by 9 points. In hindsight, it was probably a mistake to take the 2nd GMATPrep CAT. I should have saved this for the final practice test before the exam to gauge my performance prior to the exam.
- Sep 9th: MGMAT CAT (1) - 500 (Q34, V25)
Was utterly shocked by this! I know it was a month since the last CAT test but I didn't expect my score to plummet this much. I was studying during this time and I believe I focused a lot more on CR than SC and, surprise surprise, my SC score during this CAT suffered immensely (I think I got something like 3 right out of 15). Timing was also an issue for me on Quant as I realised I spent almost 6 minutes on one question and ended up rushing the last few ran out of time for the last question.
- Sep 19th - MGMAT CAT (2) - 550 (Q39, V28)
An improvement! But no where near what I needed to be applying for to the schools that I desired to get into (not super top tier schools but still schools that averaged 650 GMAT). At this point I went into panic mode, less than a week before the exam and I was scoring sub 600. I noticed that my last practice had poor SC performance so I focused on that and it paid off - my SC score improved immensely. BUT, as Newton so eloquently put it: for every action there is an equal an opposite reaction. My CR score got destroyed (got something like 3 right out of 14, sound familiar?). I really wanted to believe that MGMAT practice tests were harder than the real thing and the scores weren't calculated in the same way...but then I took the real test....
- Sept 27th - REAL GMAT - 570 (Q39, V30)
I wasn't too surprised with this to be honest. Disappointed would be a better word to describe it. Not really sure what happened. I wasn't stressed and managed my time well i.e finished on time with maybe 30 seconds to spare on each section. I ended up cancelling my score. The real GMAT ended up being a very expensive practice test.

Now its been 11 days since the test and I haven't studied at all. This was a mix of depression due to my poor score and because I just started my new job a few days ago in the Middle East. So the last week or so has been quite hectic with real life stuff taking over.

Now I plan on getting back into the rhythm as I don't want to take too long of a break.

My questions for you guys:
1) How long do you think I should prep to retake the GMAT? I'm shooting for a solid 2 months of studying; broken down into 3 hrs/day during the weekdays and 6 hrs/day during the weekend.
2) I would ideally like to take the GMAT around mid early to mid December so I can make the application deadlines for my desired MBA schools. Unfortunately, I will have to consider 2nd round applications for 3 out of 5 schools due to my poor GMAT score but this is something I will have to accept and just move on.
3) A friend of mine who took the GMAT 3 times and did pretty fantastic on it (720, 720, 750) told me that the OG questions are too easy and you should focus more on the 700+ level questions from GMATClub and other sources. Is it true? I find this really hard to believe since the OG questions are ACTUAL questions used in the GMAT. But he did get 700+ all three times so...
4) My plan is to take one practice CAT exam every week - So roughly about 8 practice tests before the real thing. Is this too much? too little? I believe one of my downfalls was due to the lack of practice exams (only took 4 before the real thing).
5) Should I save the GMATPrep practice exam for the last week before the test? Since I have already taken both the free tests I assume I will get some repeat questions and this may inflate my score. Thus, would it make more sense to do them earlier?
6) I will of course be shooting for a 700+ score, but after seeing how catastrophically bad I did the first time, I would be content with 680+. Does a 110+ score improvement in 2 months sound realistic/doable?

Technically English is not my Native language, however I went to an English school since first grade and did my Bachelor's and Master's in US and UK, respectively. I basically think in English. Hence, I consider English to be my native language.

Any advice would be much appreciated!