Hey, so I fixed that error, but now I have a new problem: all of my new unit models are lying on their backs, half in, half out of the ground. Why? I tried rotating them, but it didn’t change anything. What did I do wrong?

That would be a massive mod to make, but it would be do able. You’d have to completely rebalance the game, since most of it revolves around balancing economy and military.

Even just a Shipyard for each civ would be nice and make things a little more dynamic for the naval aspect. That way you're not overloading the Dock with stuff. The Carthaginian Shipyard would remain unique, being larger and stronger than the others. 

For a27 you can only get it by building the game. However, this is being worked on for release 28: https://gitea.wildfiregames.com/0ad/0ad/pulls/8404

The current state of 0 A.D. on modern Windows PC is somewhat promising yet still unstable. 32 bit version of the game makes the crashes (out of memory) so often that it's not possible to enjoy longer gameplays or larger battles. Is there a clear instruction how to get already compiled 64bit version OR build 64bit version for Windows OS?

You could play on special maps

Strange, it's the second time somebody posted this.