Which tower are you using in this setting? I will have a look at the code and try to reproduce then. Did I understand it correct, that as soon as you add an item it turns to be 0.1s and without items it remains 0.2s regardless of how many potions you use?
1) All at once. So as long as you keep hitting the target it stacks and the timer resets. After not attacking for 6 seconds it times out.
2) Right now the cap is at 400% for drop chance. In terms of item quality it is higher I think..
OK I did end up getting 0.1 after about 1200%. If I used let's say a painting I could have had 0.1 at around 600 with sat or ice demon. It seems items work far better then they say.
I will try to reproduce this. Although both Times the same property is affected. But maybe I still have a glitch here..