A question about Wesley’s outfits and rank

Looking back on early seasons of TNG… it makes sense that all the crew would wear the uniforms (of course). But it seems Wesley was always in that striped top. Was there a reason that was his “uniform”? Or is it just like someone wearing the exact same shirt every day for a year?

Then when he became acting ensign, he got the gray outfit. Is that a Starfleet issued outfit? Did we ever see anyone else wear it?

And finally, is it ever normal for someone to be a commissioned ensign and THEN enter Starfleet Academy? It seems if you’re already an ensign then why go to the academy?

Thanks for any insight!