You can edit skin files with a plain text editor like Notepad.  Mainly you edit the css, you can also edit the layout.master.

When designing a skin you should disable the skin cache by set these to false in Web.config or user.config

<add key="CacheCssOnServer" value="false" />
<add key="CacheCssInBrowser" value="false" />

After you finish you shoud set those back to true.

Hope it helps,

Joe

Those controls are declared in Web.config, so the problem is the way you're opening the directory in VS it does not know about the Web.config.

If you want to use VS I recommend use the source code and the included .sln, otherwise just use a text editor. Or else maybe if you open the whole root web folder in VS it may work.

Hope it helps,

Joe 

Thats how I do it, I don't know any magical short cuts. Basically I start with an existing skin that has a layout as close as possible to what I'm going for. I don't pick a starting skin based on colors because those are easier to change than layout. I make small changes and refresh over and over. If I make a change that doesn't have the desired effect I back it out and try something else and gradually it does what I want.

Hope it helps,

Joe