Greetings.
- The only incompatibility I'm aware of between Dual Wield and Yanfly plugins is weapon unleash. Yanfly's weapon unleash doesn't work with default dual wielding, it only unleashes the skill of the first weapon, and that is how it works with my dual wield plugin as well.
- Multiline formulas work in the note tags on weapons, but I don't think the code box in the plugin params supports them. Single line formulas that call other functions work great, and are probably better to use in such a case. In that case, you can pass a (subject), b (target), or any other value attached to them to the function as well.
- Dual wield and weapon attack formulas are 100% compatible. Skills that lock to one weapon use the formula for only that weapon. Individual hits from multi hit skills (and a dual wield attack) will use the weapon formula for whatever weapon is being swung.
I understand asking questions prior to purchase. These aren't cheap plugins (the cost of them combined can be more expensive than you can get MV for some of the time), and it's good to know exactly what you're getting before you buy them, for sure.
Let me know if you have any other questions.
~Ramza