Last 1 month before D Day

The last month is very crucial in your GMAT preparation. From your post, it seems that you have not yet given any mock CAT.
The first thing I would recommend you is to sit for a full length mock CAT. Make sure you give the test including AWA and IR and a ta time similar to your actual GMAT.
Once you have your score, see what areas need improvement. Drill down deep and try to bifurcate the question types:

SC: The questions test various concepts such as S-V agreement, modifiers, parallelism etc. Find out what troubles you.
CR: There might be certain types of questions that are troubling you. May be Assumption, may be conclusion, inference etc.
You need to find that out and then practice them
RC: This again can be drilled down into different types of questions and also different topics. See what questions and topics trouble you the most and then practice accordingly.

As an addition, start preparing an error log and keep a note of all the mistakes you made and the lessons you learnt from the problems. This will ensure you do not make the same mistake again.

Coming to your questions,

1. Take atleast 4 mock CATs. One per weekend and devote 2 - 3 hours analyzing it.
2. I would recommend you to revise your OG and go through the problems that you solved incorrectly on the first go. Learn additional lessons and implement them in your problem solving. You can buy Question Pack 1 for additional official questions.