Arse looks fine to me Oni (no homo), doesn't look like it comes off.
Id defiantly go wider until your forearms are at least vertical.
Also, you go up onto you traps to set the shoulders which is great, but then you loose all that tightness when you lower your arse down. You really need to concentrate and get the arch. Try and get your arse inches back before it lands on the bench.
Baz, Id either take weight off the bar, or move you hands out and inch in total every 4 sessions. Give your body a chance to adapt.
Like I said in the OP, experiment with caution. We don't want any blown shoulders just yet.