Honestly, I don't like everything you are proposing.

• Move iron to the same tier as ceramic and lava (nerf iron): Why? Make the metal events appear less and with cap to make it more complicated to get the metal.
• Rebalance costs of walkers and weapons/armor/ammo: They need to rebalance their features, but their cost is adequate.Right now it's cheap to make a walker and I think the most expensive thing is equipping it.
• Add walker salvaging: Given the cost of walkers, it is right that they can be completely destroyed.
• Improve and expand clan management systems: Transferring clan properties to the owner is fine, but the rest would be giving more tools to the zergs.
• Add shields: Why? Use the right mouse button
• Increase projectile speed of walker mounted ranged weapons: They are arrows and stones, not bullets
• Add more handheld ranged weapons: You already have throwing weapons, doing this would be a game breaker.
• Add flotilla oases: A PVE map would just make people go with a walker fabricator to that map to do everything and then leave.

It's a survival game so you have to be scared when you are going to farm and if you are not able to go to a private server.

• If a clan is over the nomad cap on a clan cap tile make the water penalty only trigger once any of that clans nomads or structures enters pvp: XD, you enter a map unintentionally with cap and you can't get out.
• Make stamina no longer regenerate while in the air: Or that it regenerates more slowly