Regarding Armor mods:
The Core Rulebook armor mods are rating 1-6 unless otherwise stated, and take up capacity equal to rating. Fresnal Fabric, Pulse Weave (in errata), Universal Mirror Material (per sq meter? How does that work in an armor mod!) and Radiation Shielding have cost per rating, but don't state their max rating, and most have a fixed capacity regardless of rating. Should their rating be 1-6 as per Core Rulebook armor mods? I must admit it doesn't seem balanced to me for them to not have capacity related to rating, I'm not sure money is a sufficiently rare resource, especially at the levels given.
I think I'd suggest those not given are rating 1-6, and that rating is used as the capacity (maybe x2 for ruthenium coating).
Does that seem right, or is it all covered somewhere and I haven't noticed?
Is Universal Mirror Material as extreme as it seems to me? The way it reads, you could wrap your deck in rating 6 stuff and anyone attacking you gets -6 noise penalty but you get no penalty? The mention in the text says you can decide in which direction you want to block the wireless signal. Given most wireless access would work in two directions I'd suggest that the noise should also work both ways, much as I would love a decker immune from matrix attack!