Not every chapter has a quest to sell the guest race portal. If I recall correctly the Amuni doesn’t have a quest to sell it. I plan on selling mine as soon as I can. They usually offer a quest or combination of quests that give 200 diamonds upon completion. They did that with the last chapter quest of donate 200 KP to another players AW. Therefore I think it’s safe to sell and any future chapters will require a different building to be built.
Correct, and the quests to sell a portal allow for any portal to be sold. Building the level 1 dwarven portal and selling it is always a valid option.