Our instructors want to know how a particular drug works in the body (action), why is the patient getting it and what are the imp s/s seen. Also, if there is a drug interaction what is it that you have to be aware/do before giving the meds. Example, if your giving Digoxin you check the HR, K level etc.You may be very good at memorizing but also make sure you understand the action of the drug, that way, you also reason out the expected s/s. Also learn the endings of the drug class.
I don't understand when you say, "most of the drugs on the MAR are the very first time I've ever seen them". From what I gathered you go the night before and get your patient info. I'm confused, however by the time you go next morning there could be some changes in the patients MAR. If you don't recognize the drug there is nothing wrong in looking over the drug book.
Don't take it to heart if your nurse wants to do her assessment first. Remember ultimately she is responsible for that patient. Instead take it as a learning opportunity and observe the nurse.
Any problem you have at the clinical site talk to your instructor. She is the best person to guide you. Lastly, remember we are students and learning things at every step. Good luck!