First, congratulations on a very good score, and your positive approach will only help you next time!
1. When I was on my last question on Quant, I had selected an answer, but did not press 'next'. I got the msg. Your time has expired. Does this mean that the test timed out on me or did that last selection get recorded? If it did get timed out then I guess I lost some 3 points, right?
To make an answer official, you must press "next." Up to that point, any selection you have made with the mouse and selection buttons is no different from simply writing a letter on your scrapboard. The last problem should be the same as all the other problems in this regard, so I believe that timing out means your last answer was not recorded.
2. What should be my plan of action on Quant for next time? Shall I do OG11 again? I have done it and know most of it. Shall I do Manhattan Quant? from which books? Tests? which ones? Advice? suggestions? pls.
You've done all the OG11 problems, but were those all done under timed circumstances? If so, there may be plenty of questions you've only spent 2 minutes on. What percentage of them did you review in detail, spending more than just 2:00? If you reviewed less than 100% of the questions, how did you select problems for review? (wrong answers only, those that took too long, ones you weren't sure about, etc...) What was your review process? (re-doing problems, thinking of alternate solutions, thinking of guessing strategies, noting traps, etc.) If these questions mention things you didn't do with the OG, then you could still extract a lot of value from those problems.
If you have been very detailed in your OG review already, you can pursue other problem resources:
--MGMAT question banks
--GMAT Focus (like the GMATPrep software, but Quant only)
--GMATPrep
Sticking with timed practice sets is a good idea. If you go over 2:00 on some problems that's OK, as long as you don't go too long on any particular problem, and as long as you can make up the time on others. Aim for a reliable average of 2:00/problem on every batch of 7-10 problems.
Finally, if you are one of our students, run the assessment reports on your CATs. You can also use your OG data. Prioritize by topic, focusing on any in which you have less than 50% accuracy.
Good luck!