Ok, I've survived the scarves and am now tackling the wristbands!  But I have two beginner's questions I can't find answers to elsewhere and would love and appreciate any help!

1) When it says for this project (and others) to cast on with 2 strands of the MC held together, where do the strands come from?  Do you use two skeins of the same color at the same time, or do you cut off a long strand of yarn and use that as one?  I'm baffled.  I may not even use this method, but feel I should know how to do it for other projects!

2) I watched the knittinghelp.com video on intarsia and it was super helpful.  However... how does it work the first time you use the CC?  Do you do any kind of knot or cast on or anything, or do you just leave a little tail and start using the CC like it has always been there?  Or is there something I'm fundamentally not getting? 

Thanks so much to anyone with the time to lend a hand and clear things up for me!