I have never heard the phrase 'to pull marks' before, however, its meaning is perfectly clear within the context of the sample paragraph, i.e., to use a legitimate strategy in an exam, a test or similar that will result in a higher mark being obtained. I would not be surprised if this phrase, or something very similar, is used in many academic institutions.
I have no problem with the use of the two comparatives in the sample paragraph. In my reading each of the two comparative adjectives is describing a different noun, and is not much different than saying, 'the grass was greener, the sky bluer'. If the writer had written, 'it's more easier to pull marks' then I would have agreed with your reservations. However, this article from Yale University (Double Comparatives) even gave me pause to reassess my views with regards to (at least) some double comparatives.