Good questions! Most xG models are shots only. Some models (think it might be Opta... can't remember - paging
Blades Analytics) record "dangerous moments" or similar which take into account things like a cross that should have been tapped in but the striker somehow fails to make contact with the ball, so it doesn't technically end with a shot.
It doesn't - xG is essentially an average of a large number of players who have taken shots from that position. You can get quite a bit of value out of this because you can see which players outperform their xG and draw the conclusion that they're an excellent finisher (Sharp is an obvious example, but if you were a performance analyst / scout you could look at data for less-well-known leagues or players and immediately get an idea of who could be an above-average finisher).
On the flip-side with McGoldrick he was massively underperforming his xG about 6 weeks ago and some of us (cough) suggested that, while he's not an amazing finisher, he had been a bit unlucky and would probably regress to something closer to his xG over the rest of the season. Lo, his xG for the season is currently just over 12, and he now has 10 goals - much closer to what he "should" have scored.
With Wilson, I'm not sure if he's
absurdly good at long range shots or just whether he's just "above average" and takes a load of them. S2 Stats on Twitter pointed this out the other day, Derby actually take more shots from *outside* the box than they do inside! And Wilson himself leads the league in shots outside the box.
Yes, I believe most if not all xG models account for shot quality which take into account the body part used to shoot, as well as the type of pass/move that led to the chance.
Same! It's also quite gratifying that United have been one of the top 2-3 teams on the expected tables pretty much from September onwards, and that we've matched that level of performance with the results.