It is surprising to see how many people, even in PDGA tournaments, that do not know these things. Good stuff. The one I'm always gray on is a downed dead branch that starts a few feet in front of your disc and extends through your lie and beyond where your stance would be if it were physically possible. My understanding is you cannot move it because it starts in front of your lie. Is this true?
No, the rule was changed in 2011 to allow moving of casual obstacles even if it extends in front of your lie : http://www.pdga.com/rule-changes-2011