It's an obscenely complicated subject.
And to be honest I don't have enough of an understanding of it to truely explain to someone what's going on there. But I would argue that very few people do except Funcom employees.
Nano Resists effectiveness also depends on the position of your aggro bar. It's not a static translation to v resist will allow you to resist x nuke if the attacker has y nano skill with z chance.
AMS as you say is visible, but effectively it's just the higher the better. AMS is used to calculate a critical, a hit or a miss against the opponents final DMS.
The Ring of Luck adds a static amount to Defensive Rating, rather than a percentage increase. The same with Add All Def clusters.
DMS is primarily based on Evades. I believe DMS to be a static value, but I believe there to be seperate versions of it for each evasion skill.
The position of the aggro bar also I think provides a multiplier for DMS, which either increases or decreases the end value used to calculate a critical hit, a hit or a miss.
Because of these issues I want to avoid an attempt to explain these further within the guide.
Inits are a much easier topic, there has been a lot of experimentation down that line so a lot of people have a very solid understanding of that topic. The speed published on weapons are accurate with 0 init and 50% aggro bar (ie in the middle) the same applies for Nanos.
Essentially... too much maths... which I have so far tried to avoid. OE rules aside.