All about choosing the right font for a website

Question

I actually have right now two questions:

1) What font faces are preferred for a website? Right now I really like \'Segoe UI\', but it\'s only available on newest Win

Answer 1

Most major browsers already support @font-face so you can use any openly available font.
Google Web Fonts hosts some free fonts to choose from:

There are also paid websites like Typekit that will host paid fonts for you and let you buy them: