That order is fine, but if you do that order you should skip the first two stories in Unfinished Tales (i.e. the two that concern the First Age). Those two will anyways be included in other books in your list, so you won't be missing out.
There are many other Tolkien books, but they're a lot less approachable than the ones you've listed, so you should probably read those first before deciding if you want more.
I have no comment regarding Howe vs. Lee, but there are other art books on Amazon. There also are books with Tolkien's own art, the most relevant of which would be The Art of The Hobbit and The Art of The Lord of the Rings, though others like Tolkien: Maker of Middle-earth and Tolkien: Artist and Illustrator are also good.
The Atlas of Middle-earth by Karen Wynn Fonstad is a great book, and almost certainly the best map book currently available for Tolkien.
Oh hey, I have the art from this calendar as a book.