Perhaps a change to the suggestion allowing for destruction of the building to avoid the pollution costs
Which buildings would you want to destroy/disable/sell if such a mechanic was available?
As to the sale of the building, as previous Civ games allowed it
In previous versions of Civ buildings had maintenance costs, so an option to sell them was important. In HR pollution is the only drawback to retaining a building and should be outweighed by the other benefits the building provides. Dirty Power Plants are the exception, but as I mentioned, they are decommissioned/removed whenever a city builds a cleaner variant.
Would supplementing the AI be that difficult for planting a forest? Do not AIs already engage in various improvements such as farming, building lumber mills, etc. which are quite similar?
Forests are a terrain feature that can have other improvements built in them (or instead of them). In terms of AI, that's a step in the decision making process that doesn't currently exist and has the potential to lead to cyclical decisions if not handled correctly.
Is there any limit to the number of resources that the game can handle?
There's no hard limit that I'm aware of, though there are a number of soft limits that take additional effort to overcome. That's not why I've capped resources where I have though. Non-strategic resources need to provide happiness and/or health; on their own and via a building. Otherwise they have no value for diplomatic trading. (Ideally they also need to be associated with one or more Corporations/Syndicates too). Every new resource is thus a new source of happiness/health and I'll explain why this matters below.
6) 9) 11) 12) 14) I am not certain I understand the balancing standard you are referring to to. The AI buildings would receive all of the same additions/modifications/bonuses. So the factors should balance.
I refer to balance within your own cities/civilization. If too much food is available too early, then cities grow too big too early. If too much commerce is available too early then it can make tech progression too fast or cultural victories too easy. If happiness is too easy to obtain (e.g. from resources) then it trivialises the mechanic unless additional sources of unhappiness are added. And so on. Available happiness/health needs to be commensurate with the growth rate of cities. Too much yield in cities can reduce the importance of good city location and land use. And other such interactions. Civ4 is a game of cumulative effects; it doesn't take much to disrupt the pace and balance of the game so I have to think holistically when adding new bonuses. Sometimes balance has to trump realism, other times realism is worth reworking that balance. I put a lot of time and thought into such things, possibly too much, but I think (hope) that's a reason why people enjoy HR.
7) As to your comment that you doubted the AI could handle the "negative" culture, please refer to my several year long testing of my proposed additions/modifications/bonuses. The testing included placing the negative culture into the AI Cities. It worked fine with no issues or problems. Indeed, I suggested that these particular suggestions would not need any tweaks to the AI and would only need to be inserted into each building's specifications.
That's good to know. Will keep it in mind for the future.
8) Thank you for acknowledging my observation that Intelligence Agencies should not be in every City. But that is the essence of my suggestion. Each Country usually has one major Intelligence Agency (CIA, MI6, Deuxieme Bureau, etc) The game (1.24) potentially allows them to be built in every (but in more than one in any case) City (if a Player have enough Great Spies) giving a Player an out of balance access to Espionage Points which should be changed (why I suggested that the Intelligence Agency should be made a Great Wonder. Unless, that change has already been made in 1.25, which I would not know about...?
Perhaps it would make more sense to redesignate the Intelligence Agency (Great Spy Building) as the Security Bureau (National Wonder). And vice-versa.
10) Yes, I understand that the Solar and Hydro Plants have reduced pollution effects compared to the Coal Plants. The essence of my point is that they should have none. Neither have foul air or water or radiation emissions that characterize the pollution of Coal or Nuclear Plants. edit: The current game (1.24) has two pollution points for Solar/Hydro - has it been changed for 1.25?
To Xyth: I made an error on the Solar/Hydro Plant comment - the current 1.24 version has them at two pollution points - I assume that you meant that 1.25 has them at zero. Apologies.
I thought they were at zero in 1.24 as well but maybe that was a bug I've since fixed and forgotten about.
17) I understand your point about Barracks. As you indicate, change the name of the Bunker to a Military Base, keep the four experience points for Armor units but also allow four experience points for Artillery units (which do not have a building providing the, to Artillery units currently in the game).
Bunker provides Artillery XP as well as Armour XP in 1.25, but I'll review it after release.
I understand that the Coliseum is already listed as a Roman Unique Wonder. However, I would suggest that the Coliseum is so universally known and acknowledged, it should be elevated to Great Wonder status. I would propose the same argument for the Grand Bazaar at Istanbul and the Sphinx and the Louvre. In an edit to my original list, I added a few items, which are not on your lsit including the Diocletion Baths in Rome which reputedly could handle 3000 bathers.
I'm not opposed to elevating/replacing UWs where appropriate but in this case there is no shortage of Greco-Roman wonders nor Classical Era wonders. Low priority at this time.