Circular knitting questions

[pandaca]

I've been lurking since early November when I started knitting, but now I have a few questions.

I've been working on my first hat on circular needles and now that I'm at the top the pattern instructs me to switch to DPNs. I don't have DPNs - is there a way to finish on circulars?

I tried switching to a smaller cord (my MIL bought me a set of Denise Interchangeables for Christmas!) but dropped a bunch of stitches and made a huge mess. Is there a way to switch cord sizes more easily?

My last question: this is the first project that I've attempted to alternate colors. The row that I switched yarn was obvious on the RS of the hat but smooth on the WS (because in circular knitting, the outside is the RS, right?). How do I do the join so that it shows on the inside but is smooth on the outside?

Does that make sense? I'm talking about how you can see where I was knitting into one color yarn with the other color. I just want that part to be on the WS of the hat.

Thank you so much (in advance)!

[ecb]

you can put the right sized needle on the front of a pair of interchaingables and anything close/smaller on the back end
and use them instead of DPN
use 2 or 3 sets
just an idea

ecb