OK, Down the list we go…
1: Gold has been working in the past. However, introducing extra currency into the economy may cause prices to rise and make purchasing hard to acquire items (glowstone, slime balls, ect) difficult for new players as there is currently no gold sink.(all introduced currency stays in the economy causing inflation.) Perhaps a solution to the extra gold is to introduce a gold to coin exchange that removes gold from the server economy.
2. Coins do not affect the server economy in any major way. The items that would be introduced don’t seem to be able to unbalance the server in any way. PvP encounters could be affected by highly powered weapons, however, that is not the primary goal of the server.
3. I can only think of a few permissions that could be made available to non-mods without potential for significant harm. Fly, Invis, perhaps superpick. I don’t really like Fly mode as it makes building very easy. Superpick may have potential for Griefing.
4. I’m not sure if a Donor region or city really fits with the server. However, there are no issues with balance or griefing.
5. Posts like this one kinda prove that everyone gets their say in how the server is run. I don’t really have a well formed opinion on this… Yet.
I like removing group restrictions upon donation. I see balance and fairness issues in giving game changing bonuses in exchange for donation. A Green name and the unrestricted ability to use flint and steel seem like very enticing things.