Search on good-tutorials.com. They have overall lighting tutorials and focus shots and such. It won't be too hard to find something good.
Sure, and you can find them by simply Googling "Photoshop Lighting Tutorial." You'll find thousands. But things like lighting and focus come naturally, with experience. Over time, you'll be able to tell when something is too busy or not well lit. There's a lighting feature in the Filters menu (Filter > Render > Lighting Effects -- at least that's what it is in my version of Photoshop). That should give you all the lighting you need for now, although you can eventually learn to add lighting effects with things like gradients. But this guy wins my respect because that's the most accurate sentence I've yet to read on this forum. Just experiment and get to know the program.
You probably could Lone. I'll check that for you. Edit: It says on Download.com that it doesn't support it. That could be because it auto installs. Anyways, it wouldn't hurt to try though. Heres the link to it if you want to try.