hello, my name is maleficent, and I am a coffee addict... I practically have a shrine set up to it...
Coffee is dehydrating... so if you do drink coffee, you should drink a bunch of water for each cup you consume.
I've seen studies where it helps boost your metabolism (if that were truly the case, i'd be the energizer bunny who weighs 110 pounds) I've seen studies where it's good for your liver as well as memory function (on a good day, i can remember my name, and all sorts of obscure television and movie trivia... I can't remember anything else though)
It's one of those things, all things in moderation are ok.. don't overdo...
I'm also coming around to the mindset that sugar substitutes aren't good for you - I'm trying, as much as possible, go as natural as possible in foods and not eat anything that has an ingredient i can't pronounce... Sweet and Low is all chemical... and can't be healthy (and i've consumed that stuff for decades) I saw a study once - and i can't recall the source, but it was that people who consume sugar substitues end up gaining more weight than people who use real sugar because the substitutes are so sweet, it takes way more sugar to get the same taste.