Your weather stripping done for and you might need to adjust the strikeplate to get the door to close against the new one a bit harder.

Very nice work! I'm curious as to what you use the room/space for when the bed is folded up and hidden? I've got a space that seems to scream for a Murphy bed but I'm not sure if it's worth it just to have a big empty spot in the middle of the room 80% of the time.

Measure 3-4 times and make sure you're "looking" at the panel and placing the measurements correctly, front vs back or top vs bottom.

Do you honestly believe that stuff you buy on Amazon has any safety standards in mind?

If that's what I was working with I'd figure out a way to triangulate from the legs back up to the bottom of the desk with some dowels or something similar. Honestly those legs are pretty spindly for a table that size, at least based on the pics.

The shower heads themselves are completely dumb non-operable devices. They don't have any valves in them and only distribute the water they are fed, from the valve. Your valve is leaking.

Nice work.

FYI for the future though, 3 - 1" long welds along each of those seams would have been more than enough. If you wanted to make them all look uniform just grind the welds down and apply a small bead of black or grey polyurethane caulk down the seam.