Congratulations, your thinking is right on target!!! It's great that you are picking up these things and questioning them.. Your instructor should have no problem answering these questions! If she is busy and your RN that you are working with happens to have time you could ask them too (when asking the RN though I wouldn't run down a whole list I'd ask about the most important question ?why is s/he taking this med) You are a student and there to learn. Don't ever forget that asking questions, being curious, and researching things when you're not sure are the best ways to learn!!!!
Things to keep in mind.. Meds are taken for multiple reasons i.e. anti, depressants/antiseizures/beta blockers for migraine prophalaxis, *some* antipsychotics are used in depression, some depression meds are used for sleep,or etc..
Another thing is some hospitals the secretary puts the med orders in, then a nurse checks it off. Now if it's a drug that causes insomnia or sedation for example the secretary may not realize this and the nurse should and change the order to in the am or at night depending on the effect. Sometimes the nurse may just check it over comparing the order not really thinking about the effect.. Kwim? So I've picked these errors up before and you may notice something like this and it'd beneficial to speak up!
Anyways I'm blabbing but don't be afraid to ask questions
and keep up the good work!