I'm sure this question has been asked before. I couldn't find it though. How many can you have? A couple of sites at the top of Google results for a 2-key word phrase have like 30 or 40? Is it okay to have that many? Do you separate them by commas or spaces? Thanks.
I guess that every word on your page, if in scope with your pages content is a keyword. You can have as many as you can fit, but I would say that they number that you should optimize for should not be many. I would say 1 or two primary keyphrases and then adjust as needed and as you logs tell you it is appropriate. maybe three or 4 targeted keyphrases max per page, but I go for one or two, well trafficked and targeted phrases and any strays I get traffic on is a bonus.
In the keywords tag you can have as many as you want. There is, however, no sense in putting any keywords in the meta keywords tag that don't appear in the body copy of your pages.
The body copy can usually focus on 1-8 related keywords. The number of keywords a site can focus on is limited only by its size.
Is the meta keywords tag important? Debatable. For Ink yes, for AltaVista and FAST yes at least for Trusted Feed programs. To the best of my knowledge they don't even look at body copy with those programs just KW, DESC, and Title. One would hope they'd put more emphasis on the body copy for pages included the good ol' fashioned way.