ACS Style is the most common citation style for chemists.
Probably not unless you plan on publishing your work publically (thesis or dissertation, journal article, etc). If you want to reuse images/figures from another author in your published work use the Copyright Clearance Center opens new window to find permission rules for various publishers.
You can also email a librarian for more help.
There are self-paced library tutorials that student can take.
Keeping your References and Notes Organized opens in new window discusses how to choose a reference manager. Also, it discusses three reference managers in-depth, where you choose one of them to try. A reference manager helps you keep your references and notes organized, which will help you when you start writing your paper.