Jumping for aerial duels depends on the situation. In some cases just contesting for it, even though you don't have a chance, can make it more difficult for the other player. In other cases it's better to avoid it, the player going up to head it will be out of position and there'll be space in behind him or out wide, if a teammate receives the ball it can create chances. There's no golden rule about always contesting for headers, so not all that bothered about it.
Not all that worried about his general play either, it's the first match of the season, let things settle down a bit.
Hopefully they'll sit down with him and show clips from last season, and the offside situation yesterday, then focus on it in training, because it's a bit of a worry that it's not exactly the first time that he goes from being in a goalscoring position to turning away from goal looking for a pass. Just hit it, doesn't matter if it's your weaker foot, from that position and distance it doesn't have to be the best placed shot to result in a goal or a deflection that we score from. Needs to be ruthless when he gets into those areas.
Needs to lower his shoulders a bit, not worrying about not playing the next match if his performance isn't great