Grass is tugh because you have variable lie. Sometimes the ball is a bit up in the grass sometimes it's deeper. Sometimes the ball settles into a little depression between a couple of bumps etc.

Matts are completey consistent so you don't have to worry about that.

Sometimes when the grass lie is really tight I'll pick u a broken tee and tee up a ball just a tiny bit above the ground to mimmick a less tight lie. I find once I've got my rhythm I try using a fairway wood (which are designed to play from the grass) and then move on to irons and wedges. Just keep thinking about taking a divot.

I like to wear my golf shoes because the toes are a bit pointy and I line up my address by first placing my left shoe a bit behind the ball. So from the point of view of building that consistent pre-address routine it probably is a good idea to wear your golf shoes.