When playing this game with friends (it's awesome), I've noticed there's a poor distinction between which powers are and aren't optional. The specific situation here is I am playing Emperor and I have a yellow district and have no gold after building something. There is also a revealed tax collector. If I choose to gain income from the color, then I will get 1 gold, then at the end of my turn I have to pay the tax to the tax collector.

Question: Is the line "You receive one gold from ... " optional?
PS: I know the phrasing receive implies that it isn't optional. However the phrasing on other characters such as Navigator also says receive but it's also possible to opt out from either choice according to the FAQ.

Thanks in advance!!

I also have a second question. Is the Emperor's power to change the king to another player optional ?

Question three : If the Diplomat switches a Manor with difference pay to someone else, and that player has a Manor, then would one of the victim's Manor's be destroyed instantly ?

Question: Is the line "You receive one gold from ... " optional?

PS: I know the phrasing receive implies that it isn't optional. However the phrasing on other characters such as Navigator also says receive but it's also possible to opt out from either choice according to the FAQ.

From the FAQ:

Q: Are you required to use a character’s special power?

A: No. The assassin is not forced to kill anyone, nor is the thief forced to steal, etc. Still, there is rarely a situation when it wouldn’t be to your advantage to use the special power.

All special powers are optional. The ability to take income from districts is a special power of the four (eight) leaders who have coloured dots.

By the same token, no the Emperor is not required to move the King token. Of course, you won't get gratitude from anyone if you don't move it.

Question three : If the Diplomat switches a Manor with difference pay to someone else, and that player has a Manor, then would one of the victim's Manor's be destroyed instantly ?

I don't believe that you are allowed to give a Manor to someone who already has a Manor. You must pick a district that you can legally have in your city to take and you must pick a district that the other player can legally have in his city to give.

I'm not 100% sure about that (only 95%), so you might want to ask FFG - or Mr. Faidutti, if you can find him - for an official answer.