So, spending a single 'A' card allows me to rebuy all the cards I drew seconds before?
Finally, do all the cards used go to a discard pile and only come back (shuffled) when the main pile is empty?
With a game this lightweight, I tend to lean in favor of focusing on the narrative side of things and not worrying too much about giving everything a mechanical representation. That said, I would take inspiration from Forged in the Dark games, with bonuses/penalties like:
- +X/-X cards drawn
- Clear X Stress
- Activate a special ability by taking X Stress
- Activate a special ability by playing a specific card suit
- Activate a special ability when you could play a face card, but choose to play a lower-value card