14" sounds about right for the pulley connected to the back of the 18" wheels. I have purchased my blades off Amazon. The optimum bandsaw blade speed depends on what you are cutting. For wood, it can be as fast a 3000 feet per minute. For some steel and other metals, it would be as low as 100 feet per minute. I mainly run mine at slower speeds for metal, but slower speeds can also cut wood just fine. Below is a website that will calculate your blade speed based on motor RPM and wheel diameters.

Calculate Band Saw Surface Feet per Minute (SFPM) | VintageMachinery.org