External Links & Number of Words

Let's say somebody offers to write me an article from his/her blog - and asks me how many links I would like from her blog to my website.

is there a maximum # of links that you should not go over in an article or is it just a matter of the blog's length (# of words)?

If I just want one link in an article is there a minimum amount of words needed in an article? is for example 300 words enough? And in addition, will an article with 1 link and 1500 words be worth more than an article with 1 link and 300 words?

What if I want 2 links in an article what is the minimum amount of words needed.
In addition, what if a link will be put on the keyword 'play slots' how many times should this keyword be mentioned inside of the article. I mean is there a minimum maximum keyword density that should be used?

Would really appreciate your thoughts on this :)

Longer articles tend to rank better. If an article actually ranks and receives traffic, the value of the link is higher IMHO. If I were to engage in this type of guest posting on someone's blog, I would attempt to write something that had a chance of ranking on its own merits...

Then again, if you are going to invest that kind of time, you might be better off putting the content on your own website ;)