I am currently building this:
I bought the fitting from them. I am not using netting after being discouraged from doing so because it does not last unless you get the VERY expensive ones. I am using shade cloth.
In terms of the MP line, many people liked the MP-53 better than the 54 though I didn't notice that much of a difference. I'd suggest you take a look at the new JPX 900 Forged or Tour too, they play longer than the MP series but are forgiving.
It was just some netting. It was strong, stiff, and had an oily feel to it. This was quite a few years ago, and I honestly don't remember. I also used a bath towel where the balls would hit to save wear, and tear on the netting.