1. Ok. Play for win. eventually you will say - "so what, I just lost 3-6 months in my life for no good reason"? Multies should be hunted and banned, and there are good tools for that already. And also, conditions may be met for the reward. Both you and your multi are in the same kingdom and you both have played 70% of the time? Really???
2. Solvable. You expect that everyone will just use 5 gold every day for just 8 hours? And even if you choose the "average time of OPs " and be protected, don't you have all night to be smashed then? What a hell are "average time of OPs" on a globe? I can always plan to launch attack when these hours expire. Are they the same for me and you? I would even make these hours silver buyable. They will raise strategies, planning, tactical awareness.
3. Yes. "Decent hammer" if you have them. Extreme disadvantage to players who don't have them! Try to defend with 5 cities against just one cropper. You can NEVER SUCCESS! Therefore - remove these, and wildly increase 3/3/3/9 (triple their number on the map).