Well, YES. What is wrong in submitting your sites each page in a website which is meant for that purpose only. And the most important thing is that you will get the quality traffic from there.
are you mad ? you want his account to be banned ? No don't do it i have done the same thing in past and got banned. So you can submit your each and every post but with a condition that you have to post other domains also otherwise you will get banned
Stumble Upon has this silly rule that you can not use them to promote your own sites. If you Stumble all your own posts, your account will be banned.
You can stumble each page, but it would be good if you ask others to do it.. if you stumble it from own id then they will ban that ID from that Domain..
Don't do it! You can stumble upon your article, and blog posts, but you must mix it in with others too.
a social bookmark would help on traffic, but I think you shouldn't stumble your own post a lot, they'll notice and then you'll get banned.
Whenever you stumble your site you must stumble other sites always, otherwise youll get banned. Besides that I would recommend you to stumble your site only once a day, not more than that.