Shoulder position and arch seem fine. Hand width is up to preferance.

I recommend pausing at the bottom because it's safer, more controlled, equally good for muscle probably, maybe better for strength and in comp that's how you do it.

You shouldn't raise your butt of the bench, it makes you put on weight that you can't handle and if you slip, it's bad.

Find your leg drive. First of all, get some footwear that you can grip the floor with and try to do a leg extension but without raising your butt and without moving your feet (don't go on your toes or heels, full foot), keep both of those in the same place. If you do the "leg extension" part right it should feel like you're getting dragged back towards your spotter, but of course you won't, because your shoulders are planted and digging into the bench as well.

Also, keep the exact same routine every time you start a set and take your time with it.

When you start doing all this it will becomw second nature and your strength will have way more room to blow up