Spyder VS1, Silver Smart Parts 14" Linear Barrel, and eVLution 3 hopper.
It doesn't matter, but I use Monster Balls, just because they're inexpensive.
None that I can think of.
This is a very accurate barrel, for a very reasonable price. I purchased one the day after I used my Spyder VS1 for the first time. And, it's extremely cool-looking. It doesn't muffle the sound of your gun shooting at all, but it really doesn't matter. You can't really aim with a vertical feed neck, but the barrel makes my gun surprisingly accurate anyway.
This product has not disappointed me yet, so it deserves a 10 out of 10.