Parents with solid kid relationships can exert a fair amount of influence into the forever more, even though you might think otherwise. Therefore, make a list of the items that concern you. Set the list aside for a day or two to allow some cool down time. Scratch those items that are really not life altering at this stage.
As for the others, plan your attack. You can drop some heavy therapy without giving up your source of concern or really even acting like you are really concerned. I got worried about # 1 sons drinking during his early college days so I frequenty slipped in stories (along the lines of general conversation) about my own youthful stupidity and that of others. Now that he is in medical school I occasionally remind him of how devistating a mis step could be on the career he wants so badly. Of course, all through the teen years I waged one hell of a nonsmoking psyops campaign.
I was always able to make progress by maintaining this stuff as constant background noise as opposed to the sudden confrontation.