It is flat.
You can bend this by hand if you need to.
No it’s not that sturdy.
Each opening is 6'' x 6''.
The gauge of the wire is .134"
The numbers you are referencing are Model numbers which apply to different manufactures of the product, not the Home Depot SKU number. Both products are listed as the same Home Depot SKU. Depending on the Home Depot store you shop, there may be different manufactures who supply the store.
Seems kind of thin to be weldable.