You really should only spend 1:15 on SC questions, so going through a checklist is going to be too time consuming to be effective. I like that you are focusing on the various categories because you will need to be familiar with those different categories so you can spot those errors quickly (ie, spotting it/its/they/them/their for pronouns or noticing the s/no s for subject/verb agreement). Oftentimes you will recognize the categories as you are reading through the sentence. If you don't see the error in the sentence itself, the vertical scanning exercise can help you spot the errors.
Idioms should not be the first item on your list - they should probably be at the end because the GMAT has been trying to remove "Americanized" idioms for some time. At the same time, the GMAT is increasing meaning-based questions, so you should add Meaning to your list of categories.
KW