Yes, I will be hanging the picture. I am getting top-down, bottom-up blinds installed so I will probably forgo the curtains.
I have angled the chairs in. Thoughts?
And plan is to get a big mirror for the wall in the foyer. Not sure of colour or style- any suggestions?

I think the angle looks more inviting for some reason. Not like you're sitting against the wall. But sounds like you are almost there! Wish I had more helpful input :)

Would you put in a rug? If so, what kind?

Should there be something under the glass table? Some kind of stools?

They look better straight on with the walls like you had them. Is there another place they might go?

The chairs can go in those two corners or angled in front of the two windows. Those are really the only two options.
I would like to incorporate more black in the room if possible...

Love the art! When you hang the art make sure the top doesn't line up evenly with the lines on the wall tile. Slightly higher would look great.

I have always really liked the styling of this glass table.

I love cactus and succulents, but here I definitely think you need fresh flowers. I like to use one color and lots of them. Also, the room will look more homey without the two spare chairs. Hopefully you can store them elsewhere.

Instead of a mirror next to the door look for something with a little more flair.

An antiqued floor mirror. Not sure of how the squares will look with your tiles?

A large framed fabric or scarf?

Everything looks great. Chairs on back straight and add nerow pillows on the back. In the entry, bench with acrylic legs to mimic your dining table and mirror behind it. Large framed mirror, no extra details. I also think that entry can have round rug.

Thoughts on these toss cushions from McGee and Co. ?

Or maybe these. Half the price.

https://www.houzz.com/products/lumbar-linen-pillow-cover-ocean-embroidered-lumbar-pillow-ocean-with-pillow-prvw-vr~104925054

https://www.houzz.com/products/grable-modern-milk-white-curl-long-wool-lumbar-pillow-11x22-prvw-vr~50193743

Bought this lamp for the bedroom but it was the wrong shade. Keeping it because shipping it back will cost too much. Does it work here? Trying to style this table.