[Elecraft] Elecraft keyer chip

[David Toepfer]

I suspect that Elecraft makes their keyer chips work as much the same or similar as each other, but I am mostly concerned with the KX1 and also the KX3 keyer chip:
 
1)
Are there any functions of the chip that are controlled by and necessitate the use of a paddle?
 
2)
If there are, do any of these require that I have acess to a dual (iambic) paddle (to engage both dit and dah at the same time), or are all paddle-controllable functions just as accessible with a mono paddle as well?
 
David, k3tue