Mice!

No, never. Classes (or "archetypes" as you call them) would shatter any realism or believability this game has. Skills should come with practice, not in preset configurations because, you know, that's how the world actually works.

NO Player's shouldn't spawn with a firearm, but they should spawn with or have easy access to improvised weaponry. Clubs, tire irons, boards, hammers, etc. Nothing that allows someone to grief/deathmatch, but something that allows a player to deal with zombies - to a degree.

Loving this idea, but the 'Time', 'Blood', and 'Chance to break bones/bleed out/infection' penalties are unneeded. The chance that it could fail and a double tap are penalties enough. A 'getting up' animation would be necessary as well, so people who are playing dead just can't pop up immediately and shoot someone.

Yeah, no. Most of this is just fucking stupid.

He probably just sucks

Happens to me all the time. I believe it's a bug in the current gear & zombie spawning system. If all you find is backpacks & no zombies, alt+tab & wait several minutes for gear and zombies to spawn. That and connecting to the closest server you can should be your best bet. Nevertheless, it is a very annoying bug.

Then the zombies themselves don't have to be handled by the server, instead a horde is represented by a single entity, handled server-side. Once they are near a player, then the zombies are spawned in their client.

A sanity system would definitively up the realism and immersiveness of the game. It should be very subtle and confusing at the same time, gunshots in the distance, the "bug noise" for when dead players are near when there really aren't, etc. Another thing, two types of sanity damage should exist - short and long term. Things like dehydration, lack of sleep, loneliness, cold, and zombie encounters can be fixed by company, a fire place, sleep, etc. However, very traumatic things like close-up murder, lots of dead bodies, and witnessing players die should leave a permanent impact on a player. Things like visions, wild hallucinations, and panic attacks should occur. These symptoms can only be cured temporarily with things like alcohol & painkillers (Can't think of anything else, maybe prolonged company with someone else or gaining humanity could cure a player).

Great idea, Kyrah's is good as well.

Will the horde move based on gunfire/noise, or will they just seek the nearest (group of) player(s) to them on the map? Good idea, should add more tension/randomness to looting, basing with others, etc.

Yes, but some sort of customization should be given to players, even if its just 3-4 different skins to choose from. Perhaps there could be a different way to tell if someone is a bandit, like maybe having bloody hands from looting players, idk.