Arial is basically Microsoft's rip-off of Helvetica. It didn't feel like paying royalties to Linotype. My favorite is followed by: Can't beat good design.
Monospace fonts Cheesecake, Courier New is what I would use for that in Word, although for most things I just leave the font at default as that is what my teachers prefer.
It's getting better. You wouldn't use it for anything other then intro text or headings but it's definitely a brilliant little bit of javascript.
Neither, I use Trebuchet for everything, best font ever I do lol at how places still print letters off in courier
My personal preferance for the last few years would be Trebuchet, I use it for all my college work. But out of the 2 choice... probably Verdana, looks better on screen. EDIT: Good to see i'm not the only one
Well for headlines and such, there's always SIFR (at least until downloadable fonts through, I think, CSS3 come along). Not so much for large blocks of text though. I tend to use Verdana on websites (though in some places, I do like a nice serif font), but then again I also tend to hire a designer because I'm useless at this kind of thing.