Hi Pedro

To answer question 2, you wouldn't want to edit the CSS/HTML of a published course as it's the compiled output of many different files.

You could either do 'export source' from the authoring tool to get a complete copy of everything to work on outside of the authoring tool or you could just download the framework directly.

Once you're happy you've got everything working OK in the framework, you can bump the version number in your theme's bower.json then upload it into the authoring tool to use there.

There's a guide to amending the 'vanilla' theme here.