Order of events

I know the rule book states that cards act in the orer they entered the field, but I still have some questions. 

Let's say we're playing in the sewers.

I'm playing Ra, you are playing AZ. You bring out your Focused Apertures in round one. On round two I bring out Imbued Fire. Now all damage is fire damage. But your card was in play first, so do you add your +1 from the Apertures before applying the effect of my card? 

Now let's say Irradiated Cyclohexane Vat comes out. Do we add our +1s to damage because our cards were out first? 

This has been discussed extensively. My apologies for not having a handy reference.

The rule of thumb I developed for myself based on the discussion is that one determines the type of the attack before applying any increases or reductions.

It's the FINAL damage type that is applied, so the damage would only be +1, because it ends up as toxic, and therefore never was fire or cold.

How would you guys rule on this?

Fighting Voss.  Ra had Imbued Fire out.  All hero damage is fire, so we can't kill the Firesworn.  Expatriette draws Liquid Nitrogen Rounds.  Think that would work?  I ruled yes.

I would say yes. I assume you that (since all the cards apply in order) the last one overrules the others.