I noticed the same issues.
For stamina, I copied HP, 3 ST, When ST == 0, then you can't flee.
Horde, everyone attacks per turn. I roll at 1d6 to pick who attacks first each round (1-3 player, 4-6 a Z) -
2 Damage weapons is for when you find survivors.
Infection, just as you described,
Medkits are used anytime, anywhere, it's a get out of jail free card. I use them at the end of a turn.
Food is used as a choice of move, search or rest. Resting is the only way to get stamina back.
So much is really based on story telling. No so much on hard rules. Tell a good story 1st then follow a rule.
A full game can take as short as 20 minutes to as long as 2 hours. So much depends on how much you want to journal.
If you journal, as chatgpt or gemini to give you 35 different location that a small town would have. Then ask it to provide a one or two sentence describing the location. This can give you the 25 locations needed to play the game. I will put the list in a spreadsheet and randomly assign 1-25 and discard the rest. This gives me flavor text when journaling.
Best of luck.