580EX II as a slave flash – 2nd curtain sync, HSS?

[Worldinaframe]

Dude, I don't see a photo credit! That sucks! Could probably request for it to be added, even though it's been up for a couple of months....?

Nice mood lighting. Could use a little more light in the eyes.

[thinslicing]

Do you always have to turn on hss BEFORE you set your 580exii as slave or is there a way to turn on hss WHILE it is set as slave?
Also, is there a reason why 2nd curtain synch is not available in a slave 580exii (technical or marketing)?