KidCo Universal Gate Installation Kit, Brown

What is the depth/thickness of the 2 smaller blocks of wood?

I have a banister on each side of the stairs, will I need to purchase two of these kits?

What are the dimensions of the wood? The description says .75 x 36 x 36 but wouldn't that mean the wood is square shaped with 0.75 thickness?

Can I use larger zip ties if my bannister exceeds 4 inches?