No. Attacks cause Bleed.
No, only 1 at a time, although you could have 1 Bleed, Fire, & Poison DoT at the same time.
An enemy can be affected by all six DoT’s at the same time. In the Case of Bleed, Fire, and Poison, the highest damage of each is in effect until the DoT time is done, then it starts over with the next highest DoT. A higher DoT will take the place of a lower damage DoT. But only one of each DoT will be in effect. so no 2+ of any DoT at any time (except for Shock, which stacks for 5 seconds, 4 stacks max).
Weaken is basically a damage multiplier. And the damage from Weaken isn’t affected by Map Element Resists & Immune. If you’re using an Ice weapon on an Ice Map with +100% Weaken vs. an enemy Immune to Ice, your weapon will do 100% of the Weapons damage. Weaken is also a % chance to work, so any Weaken under 100% is a chance to do Weaken DMG, like +30% chance for 30% Weaken DMG or +90% chance for 90% Weaken DMG. And it isn’t negative damage (many players, including me, thought it was like this). Weaken can go up to +200%! +100%+ Weaken affects every attack. I also found out that not only does Weaken affect your attack, but can also affect your damage DoT’s! (at least, I’ve seen my DoT’s cause Weaken, it could be a bug).
Bleed, Fire, & Poison DoT DMG is based on your attacks damage. If your attack does Crit DMG or Deadly Strike, then those DoT’s will be based on that damage. Also, Bleed, Fire, & Poison DoT’s also have a chance to do Crit DMG & Deadly Strike. On a side note, Attacks and Fire, Poison, & Beed DoT’s can cause Crushing Blow if you have Crushing Blow on your Equipment.
The description on the Weapon. If you have at least +50% Dodge when you activate Stealth, then you will Dodge all attacks.