Zill: I didn't see any noticeable effect, but then again the only available map was Sandbox (matches couldn't be joined, unless it was practice mode).
Shadow: It fires one mine per clip. The mine is fired a fairly short distance before it stops and a balloon comes out the top of it. The reload time is very short. Maximum of five mines (per gun? Per ship? I don't know). Once you fire a sixth, the five previous ones detonate. You can make them detonate by shooting them, or drop (REALLY quickly) by taking their balloons out. I didn't see any time limit. I'm pretty sure it does piercing (definitely) and impact (maybe), and it does a whole lot. Running into one with my Mobula wiped out the armour and a bunch of guns and engines.