580 ex 2 flash question

[pj]

I need this to go on top of the camera



and then 2 of these for my 2 580 ex 2 flashes (one as master, one as slave)



and that 's it. Just want to be sure I am buying the right stuff.

Thanks,

Pj

[pj]

Ok, so for 2 x 580 ex 2 studio set up (and possible outside work at some stage) with the flashes on tripods,

I have to buy just 1 of (to fit onto the camera)



and that's it, that will set off the 2 flashes off camera, or do I need pocket receiver for each of the 2 flashes.

Also,

Units sold in USA use 344.0 MHz
Units sold in Europe use 433.62 MHz

Does it matter if I buy iot from usa, does it find the 444.62 frequency itself or can yuou program it into it?

I'm a beginner here so sorry for sounding completely dumb here.

Thanks,

Pj