It's difficult to make generalisations about line spacing, because so much depends on the typeface you're using. On the web, we normally specify a line-height relative to the font's size, but factors like x-height (or, if you prefer, how prominent ascenders and descenders are) and the line length are also important.
As for tracking, not letterspacing lowercase is a reasonable rule of thumb, but a lot of rules need to be bent when you're setting small text. A lot of the same arguments for bending the rules also make sense if you're displaying text on low resolution media like computer screens (less so on modern high-dpi technologies like Apple's Retina products) and sometimes also if you're setting inverted text (light against a dark background). As always, you have to take the whole picture into account and adjust your typography to your content and your medium.
As for tracking, not letterspacing lowercase is a reasonable rule of thumb, but a lot of rules need to be bent when you're setting small text. A lot of the same arguments for bending the rules also make sense if you're displaying text on low resolution media like computer screens (less so on modern high-dpi technologies like Apple's Retina products) and sometimes also if you're setting inverted text (light against a dark background). As always, you have to take the whole picture into account and adjust your typography to your content and your medium.