Yeah for sure these sound like great changes. Cash Meister sounds like a great addition for the hardcore players and Prepper also works wonderfully both for a "easier" addition while making sense in the setting. I can imagine numerous special abilities a dog companion could have in the game, such as sniffing out animal carcasses for meat/bones, luring/distraction/fighting (All making sense to have risk), among other things.
Search yeah, it makes so much more sense for search/scout to be used this way as when I was searching I was really just wondering if it did nothing but just scout ahead, seeing you confirm that it does just do only that makes me agree with your idea for expanding the system, as the energy cost of searching vs just clicking A twice is monumental, finding a way to get keys both helps with weapon durability management alongside giving search a new use. I agree fully with those idea changes.
I could also see alternative ways to enter a house with more risks. For example, as it currently stands, you use a weapon durability to break down a house door, even on houses with very obvious easily shatter-able windows attached to it. If you can't find a key, maybe there could be window breaking as an option, with the caveat that you are making a hell of a lotta noise(Though I will say breaking down a wooden door is also loud, but I digress), making it so that either A. Nearby Zombies may attack you. B. Faraway zombies may hear it and start moving to your location over time. C. Some type of Mixture of the two. Or D. just the good' ol simple chance that a zombie encounter occurs. So you can have multiple options to gruel over. Making you either waste dura, potentially have to fight and waste resources or waste resources to have a chance to get a key. Stays in line with the game's management system.
I will prolly have more ideas come to mind as you reply, but I draw blanks a lot when it's just me and my own thoughts ahahaha. I hope to help in the best way I can that I think makes sense for a game perspective but also your vision. I am always happy to give feedback, whether it be for the jam or even outside of it I am always up to discuss my opinions on the game as I do wish for it to succeed and I enjoy it quite a lot.