Hi,
I am new to this forum and to GRE. Recently I took gmat for the second time and could not score good-580. Since my aim is to pursue MIM from a premium college like HEC, ESSEC or ESCP in round 2, thus I need a good score that is above 325. I am not sure if I should switch to GRE, but many people have suggested me to do so (including my consultant)

Please help me clear out certain questions regarding GRE.
I still have no clue about:
1. how does the scoring pattern work on GRE?
2. What is a competitive sectional score required?
3. How does negative marking or the penalty system works here? What if you are unable to attempt last questions or do not attempt some in the middle?
4. Do we need to take the exam 20 days before the application deadlines because unlike gmat, GRE does not give you the result instantly?
5. How does score cancellation work on GRE? Can we cancel it for free or paid (please mention the amount) once we get the result?

PS- I wrote the Manhattan gre free test today in which I scored- 304 (V150 Q154). Definitely felt it way too easier than gmat and can do much much better in quant next time. I'll keep updating below as I keep taking mocks.
Secondly, there was some disruption in the test, I had just started with the last quant section and computer displayed that the test was over. There was no timing issue.

Help me with an article that briefs or gives an overview of the GRE test with each aspect.
OR
You can answer the above questions and suggest me a good study plan.

THANKS IN ADVANCE!