Hi and welcome. Check out the section for 'Beginners". That might answer some of your questions. The smallest string is an E (when played open - in other words, when you just strike it without pressing down on anything).

As far as timing, you might want to look into a metronome for practice. That'll help. As far as the timing for a particular song, personally, I find it easier to just play along with the song.

Hope that helps. Again welcome to GT. :)