Build Mechanical Questions for Flameblast and Doriyani's Prototype! (How they work in PoB)

Hi there!

So I'm working on some new builds, and I have two questions about how PoB handles certain calculations.

1.) The first question is very simple and has to do with Flame Blast. When you see the 'cast rate' while having flame blast selected I assume what that is trying to represent is stagers per second, right?

In other words, if we assume an unmodded 10 stage max flame blast, and my cast rate on the PoB is say 4.5. That's telling me that I'm casting 4.5 stages a second, so my time to do the 'average hit' damage on top will roughly be 2.22 seconds? So I'd have to divide that average hit by 2.22 in order to get the non-ignite *hit* DPS of the skill?

I would assume that's correct, but correct me if I'm wrong there

2.) The second question is about Doriyani's Prototype and specifically how it interacts with reduced resistances.

In PoB. I have Crown of Themophile (53% reduced lightning) and Annihilating Light (70% reduced lightning). Interestingly, if I *add* lighting resist to my gear, actually reduces my lighting resist in PoB. So for example, I currently have -57 lighting resistance in PoB. However, when I'm actually in game and using the same setup my lighting resistance won't go below 0.

Here is the pastebin for the latter.

https://pastebin.com/45bxKXN0

I have some ideas for why I'm able to go negative on PoB, but I'm not sure why it won't translate into the game.