As far as dpi goes, I believe 300dpi is used in print. Since your work will be on paper, as opposed to rendered in a browser, you'll want higher pixels per inch.
The font choice depends a lot on how the pharmacy wants to promote itself. Serif fonts often convey a more professional feel, while sans can seem more laid-back and easy-going, so to speak. Talk to your client(s) about what kind of image they want to convey and design accordingly.
You might find some useful info for your project in
this article I wrote a few months ago.
Good luck and keep us posted!