Specifically, the number and the quality of outlinks? I've seen this guy selling links and he mentioned these points, so I was just wondering if how true is that?
Yeap outlinks from your site will affect PR. From what I heard, more than 15 outlinks will drain quite alot of PR from your site. But then again I aren't sure about directories, they have tons of links yet their PR stays :S Maybe google has some special towards directories.
do you need a book written? if he was giving advices without any idea, take the opposite as true dude