The Montreal GM is a whiz at reading the defensive tea leaves. Of course, since you're both in the Continental, he may not want to help you too much
Personally, I think ZR and EFF are useful, but EFF more so because it seems (from what I've read) to measure the same thing as ZR, but instead of as a counting stat, it provides an average (with 1.000 being league average). So anything over 1 is good, anything under 1 is bad. ZR measures the same stuff, but if a guy only plays a little, it doesn't tell as good a picture as EFF. Of course, small sample size applies to EFF in that case too. But it's easier to say - 1.100 means he's good, .900 means he's below average.