I'm not sure quite what you're after there for the first question. You can set the brush loading in the left panel to 0% and then use the brush to pick up and smear around the tube paint if that's what you're looking for. Each time you do a new stroke it'll tend to pick up from the tube stroke as there's a fair volume of paint there.
Can you tell me a little more about what you're trying to acheive with the colours? if you're trying to save changes to an already existing colour set, you'd need to choose "Save colours" from the drop down menu in the colours panel. If you've downloaded a .col file and want to use it in your art, you can select "Load colours" from the same menu in the colours panel and then browse to and select the downloaded file.
The colour samples panel can be accessed from the Tools menu "Show colour samples panel" or by pressing "S". Hope that's of some use!