yeah, no prob. yeah, a 3 in 1 has the two ESC's, a gyro and what's called a mixer that controls the proportion of the tail motor spinning to the main motor. Usually the tail spins about 6 times faster than the main rotor. The 4 in 1 is just like kevin already explained =)

the 2 in 1 has the 2 ESC's, one for the main motor and the tail, and it also has a mixer in it. You're right about the 1 in 1. It's just called whatever it is.