#1 a node already gets more votes because it's linked, you needn't enforce that effect. In the end, a node is upvoted when someone thinks it's good. A link has nothing to do with quality, it's a link. It's the decision of the one who follows the link whether he thinks the node is good or not. You see we're walking in circles: You cannot improve the way nodes are being up/down-voted as it is perfectly fair.
#2 Nope, that's against my sense of democracy, sorry. XP does not mean anything and if it does, it doesn't make your vote weigh more.