>>3. Word stems. Do the search engines count word stems when counting for spam? For example, would the words 'fish, fishing, fisherman' count as three instances of 'fish'?
>Yes, that would be three instances of "fish." Try to always use the longest form of a word. "Fishing" will come up in searches for both "fishing" and "fish."
even though "fish" will find "fisherman" , isn't it a lower relevance than "fish compared to "fish" ?
>>4. Limits. Are keyword lists limited by number of words or number of characters? What are the limits?
>Generally, it's the number of characters. I'm not sure if the limit is the same on all the search engines, but the limit I've always heard is 1024 characters. Of course, the more keywords you use, the more diluted they get, so it's best just to use those keywords that are most related to your site, and try not to use any word more than twice.
I'v heard that the optimun is around 100 charecters