And will triplets almost always start right at the top of the beat, like would you ever see 3 quarter note triplets, but starting on the "and" of the beat? How would you count out stuff where you kind of have to subdivide a single beat into 3's as well as into
 2's or 4
 's for regular eighth or sixteenth notes? (sorry if this is all jumbled, I hope you understand what I mean though).
something to that effect could happen, on a larger scale, for example you could have quarter note triplets starting on beat 2 or 4. but effectively what that would be is 8th note triplets hitting every other one. for example, take the percussion/hi-hat accents in that song 'everybody wants to rule the world' that's doing this. it would be not practical to write it as quarter note triplets, you would want to write that as 8th note triplets alternated with 8th note rests, starting with a rest, and lining up with the downbeats on 2 and 4