Don't worry about any foaming when you use pellets to dry hop. It is not an issue. You may be thinking about some brewers who experience boilovers when adding pellets to the kettle. Do not bother adding your dry hops until you are about a week or so from kegging or bottling, though.
I don't know anything about using less priming sugar, though, unless you think a lower carbonation level is appropriate for your beer or you think you may not have completed your fermentation. If the latter is the case, then I suggest doing what you must to complete fermentation, rather than guessing on what you have left.