I'm guessing chiefs have to attack seperately to lower the loyalty succesfully. You can have up to 3 chiefs in your capital, but you can't send all 3 in one attack and lower the loyalty times 3, right?
You could - and should - send your chiefs in one attack and gain the same result.
Can i build the Palace and demolish it in several villages in order to have 3 chiefs? You'd need the palace to be able to use all 3 of them for conquering 3 villages but you could still use them to lower loyalty even without any palace/residence?
Yes, you can build a palace, train 3 chiefs, demolish it and build it in another village where you can again train 3 chiefs. Theoretically you can use up to 3 expansionslots in every village, but it's really pricy and if they die in an attack you have no option to rebuild the 3rd chief while your palace is in another village.
You can fully use every chief regardless of there being a palace/residence in the village, the expansionslots are bound to the village not the building you trained your chiefs/settlers in.
Last but not least i wanna know how much loyalty-decrease is to be expexted from each chief. How much difference is there between roman senator and the other chiefs?
You can use this tool to calculate the effects of the different chiefs in combination with population etc:
Kirilloid Conquering calculator
@Be2-e4: Sei mal nicht schneller als ich, wenn ich schon mal was schreibe