I'm going to join. I LOVE stranded colorwork! Love the look, love doing it...
I got the Sipalu Bag
kit for Christmas... I started it but didn't have the needles right and had to rip out. So I'm going to start again... (though I doubt I will finish it this month)
I've make the Baby Booties you linked to here
I hold both strands in my right hand and don't use any tool, I keep them separate with my knuckle. And with some practice I have gotten it where I rarely wrap both. For me the tools made it hard to get consistent gauge and feel what I was doing.
This will be fun!