I have 3 teens age 13-18.
1. Homework almost always late or incomplete, to the point where teachers are emailing me. Not due to a lack of opportunity. Did they used to do their h/w perfectly or is this continuation of same-old-same-old?
2. Complete lack of impulse control with food. Eating enormous amounts after school and in the middle of the night including food set aside for dinner, sugar out of the bowl, peoples' birthday treats. Will hunt out that is hidden away and hide wrappers all over the house.
Could be Normal, sigh, but maybe b/c I think OP is exaggerating how constant it sounds. There are a few funny stories about DC midnight food raids in our household. Although DS13yo hasn't started yet & thinks it's weird (he's also had the sum total of one spot in his life so far, not really doing puberty). I do find the 13yo mini binging on his sweet stash which he never would have done 18 months ago.
3. Lack of respect for parents' privacy and belongings e.g. most recently, rummaging in bedroom for hidden Xmas presents.
mmm... borderline normal. However, DD regularly raids my clothes & jewellery & pisses her brothers off by using their favourite pint glasses Other DC were more likely to do this when younger. Scold & set firm boundaries. Presumably OP doesn't rifle thru their stuff, keep harping on that point, about reciprocity.
4. Minor damage when angry e.g. denting furniture by slamming something down too hard, losing patience and forcing a fiddly lock, breaking it. That's careless & pushing boundaries. Again, calmly reading the riot act would be called for, escalate to removal of vulnerable items if required.
5. Terrible attitude when called out on any of the above e.g. lie, deny, blame brother, go on attack. Completely unrepentant. Don't get emotional, set firm boundaries. Do a quick sharp scold, notify of future consequences if it continues, & move on.