We didn't have to make "med cards" but maybe it's just a suggestion to help you study. It definitely helps if you can see all the info at a single glance by putting on an index card: the class, generic name, trade name, contraindication/precautions, category/schedule, dose, routes, etc. and all that. I remember I used to make grids and that helped me tons because if I didn't remember something specifically, I can remember where it was written on a grid (esp. if I grouped it in 3's because I can remember if things were written in the first, middle, or last box...just something I did on my own) and that helped me connect things together, I hope that makes sense.
To me, the 310 exams were the most unpredictable. You're definitely right that it's not all going to be straightforward from memorization. It's going to be questions like from the NET exam, where you really have to think, haha. I remember I thought I did so well on the first one but ended up making an 80, if I had missed 2 more I would've failed! Then on one that I honestly thought I did awful on and pretty much felt like I failed, I actually did great. Some of it comes from what you learn/do hands-on in 320 (lab) because the classes tie in together. Pretty much, read the questions carefully. If it asks for assessment, make sure the answer is an assessment not something that would fit into "planning" or "evaluation". The answer is never something a doctor would do, it'll always be from a nurse's standpoint. Just think of the NET, if there are 2 opposites, most likely it's one of the two; if there's an answer that is considerably longer than the others, it's probably that one because it umbrella's the others, etc. I hope this helps!
Good luck on the vital signs competency! =)