Authority Site Url?

I've been thinking of starting an authority site in the health niche.
I know it might be one of the toughest niches to get into but, "you'll never succeed if you never try".
I want the site you reach into 3 "niches" within the general health niche itself. ex Muscle/body building, weightloss etc.

Since I don't really have a specific keyword (for the whole site) to target, should i just go with a short and "nice" looking url related to the health niche in general? (to make the visitors remember the name, instead of "pleasing" google in the url matter)

How important is to have a keyword in the url of an authority site?

Thanks in advance.
/Izerman

PS: Don't worry there won't be a crappy [Journal] Thread

Another question: What is the "best" CMS to use for an authority site?
/Izerman

anyone? (bump)