It's awesome to hear that it's still being developed, and those ideas all sound good! I'll definitely keep an eye out for future updates (though I totally understand things going slower than intended, hahaha). Great job once again!
That's a good question about the cards! I couldn't remember if I'd already drawn them or not, but doing some very quick testing (with just a single "-3 heat for nuts" upgrade), it seems so far that:
- When cards are already in hand before buying the upgrade, it has no effect on the heat meter
- When cards are drawn after buying the upgrade, it does affect the heat meter as expected
- But in both cases, the 🔥 number on the card doesn't appear to change

As a side note, it's a very minor thing, but when I started a "skip tutorial" run just now, I noticed that enemies sometimes have the wrong sprite during the slide-in animation—specifically, they seem to often show up as a Large raccoon when they're actually a Medium or a Nurse (I'm not sure if this happens in other battles too)!