Just to add my thoughts, yes, the GMAT is tough. Yes, students often are surprised when they get bad scores after minimal studying, and it's common to underestimate the difficulty. However, if you are aiming for a 700+ and you're a non-native speaker, you can probably expect a bare, bare minimum of 3 months of study to prep for your first attempt (and you may need to take it 2 or 3 times to break 700).

I'm not sure how generalizing the sections in this way would affect your studies. You still have to do the MGMAT SC, Powerscore CR, Quant review, etc. You still have to build a solid strategy for EACH question type. You still have to know the OG and GMATPrep cold.

I don't agree with your statement on SC at all. It tests specific grammar rules and certain GMAT "preferences" that can absolutely be learned. In fact, you can do a lot more learning by rote for this question type than any other on the GMAT. Being a native speaker helps, obviously, but I would say there are occasions where what "sounds" correct is actually WRONG. You'll need to work extra hard here as a non-native speaker, both in learning the grammar and focusing on the MEANING of each sentence.

Don't underestimate the work you'll need to put into CR and RC as well. I wouldn't say RC is necessarily "easier". In fact, I think it's the section most students prepare for the least because they think they can skim and get the correct answers without really taking notes and slowing down to learn how to take apart the rhetoric of the passage.