Should I use buttons or links?
There are differences as to when a button should be used rather than a link. UX Movement wrote an article about this, and they came up with a simple rule: Buttons are used for actions that affect the website's front-end or back-end; links are used for navigation and actions that don't affect the website at all.
Should links look like buttons?
In Resilient Web Design Jeremy Keith discusses the idea of material honesty. He says that “one material should not be used as a substitute for another, otherwise the end result is deceptive”. Making a link look like a button is materially dishonest. It tells users that links and buttons are the same when they're not.
How big should buttons be on mobile?
Studies by the MIT Touch Lab suggest that 10mm × 10mm is the best minimum size for buttons on mobile due to the average size of fingertips.