There isn’t also just beat but also rhythm but when you use rhythm you can count it out by either counting it out as well as shouting it out. By subdividing the rhythm you time it out while keeping the beat.
Chords are when 2, 3, & 4 notes are combined. A harmonic chord is done with three chords while demolished chords are done by a third chord going behind the others. When 4 notes combine they make a 7th chord. Most chords are done with cadences, triads, & the main tonic note.
A tonic triad is formed at the root which is starts with an A minor then goes all the way up to the melodic minor.It really doesn’t matter what version you use as long as you feel comfortable using whatever you prefer.