Which of the Bigbook Verbal questions types should I study and which are not helpful?
Should I just be studying their TC and Short passage RC or long passage as well as as the “similar relationship” and “opposite” questions?
You can do the TC, short-medium RC passages and even some of the Critical Reasoning questions they have in the Analytical Ability section (optional).
You can even try some of the long passages (if you have the time) to test information retention and concentration. For these long passages, though, you may skip doing the questions.