"Will I also need the stainless steel riser...?"
No.

Actually it will depend on your local codes.
In most cases no is correct but I have run into some local codes that would not allow the island type trims up against the wall even if it was tile.

Do check with your local code, as jakvis said. There was a previous gw thread on this with thoughts and pictures that you might be interested in. Follow the link below.

Here is a link that might be useful: Question about gas range & backsplash