How does Damage Reflected work?

I've searched high and low on the subreddit, wiki, official game guide, and build compendium, but I haven't been able to find a straight answer about how Reflect works. Here's what's on my mind:

1. When damage is reflected, does that mean that the portion reflected doesn't affect your character? i.e. if you have 50% Damage Reflected and (edit: with no other armor/resistances) are hit with 100 damage, do you take 100 damage, or 50?

2. Do Damage Reflected stats stack additively? i.e. if you have two things that grant 50% Damage Reflected, are you reflecting 100% of incoming damage, or 75% (50% of 50%)?

3. Does Damage Reflected apply to all types of damage? e.g. does Damage Reflected apply to retaliation damage? Can Damage Reflected reflect damage that was reflected?

4. If all of the above questions are true, does that mean that once 100% Damage Reflected is reached/surpassed, your character is no longer capable of receiving damage from any source?

The final question is the thing that's the most intriguing to me. Thanks for the help!