Great post and points - but it's always hard to make rules like you suggest without damaging others unintended.
E.g.: You could link to external posts more than 3 times a day without being a bot of a spammer, and it could be a pain in the ass for the average user.
I agree 100% but I as mentioned i would limit refering to own internal posts. Because that is what people are trying to promote mostly without having any relation to the blog where they are trying to promote it. I don't think its an issue if you post a recipe for a nice cake below a recipe for another nice cake. But if you post a tutorial on how to farm cows on a post about smoking weed ... well then this doesn't really match and can be annoying for everybody. In particular if you are interested in relevant content.