repeater questions....
I think you can’t, the game will automatically assign set 1’s off hand to set 2’s off hand if the latter is empty.
1.(With P/P+P/null) Stealth> 1 > Unload > Swap > Repeater [Has anyone experimented enough to see if this is dmg is worth?]
As mentioned above, the P/null set will indeed become a P/P on your action bars.
2. Does the tooltip suggest that the dmg from repeater out scales unload’s dmg?
Also note that Unload’s skill tooltip counts individual shot damage, not the total. (from the wiki: The damage listed in the tooltip is per attack, not the sum total of all attacks like for most other skills). So using the numbers of my current pistols, Repeater does 5 shots for a total of 1195 damage, while Unload does 8 shots at 397 damage each or 3176 total damage. So no, Repeater does not in any way do more damage than Unload.
3. With the Initiative on Swap trait would it be easier to manage a P/P + P/null weapon set? Especially now with the on demand stealth from the Dodge Leap finisher inside of Black powder?
Initiative on swap trait is actually pretty great when you’re using two of the same set (approximately 30% increased initiative gain), but then you lose out on a lot of utility potential. Most of the thief sets are very limited as is, P/P leaves you lacking mobility and aoe, shortbow is pretty much useless for single target dps, and all melee sets have terrible options as their ranged moves. So without a second weapon set to make up for what the first one lacks, it becomes much harder to adapt to unpredictable situations.