to build it you have to select a builder
No, only on land.
To build a castle in Age of Empires 2 trial version 1. You have to first advanced to the castle age. 2. Then you have to click on military building icon. 3. There is a small castle icon. 4. Click on it. 5. Then choose the place where you have to build the castle. And your castle is ready now.
Age of empires 2 is age of kings. So yes. Age of empires II: The Age of kings
2... Age of Empires age of Kings & Age of Empires Conquers Expansion
1. Build a Capitol. 2. Select the Immigrant button.
no
Build a market or dock further away and destroy your old one. And build more trade units. Spanish team bonus gives 33% more trade profit. Or capture relics to supplement your gold supply.
Yes 2 of them age of empires dynasty and war chiefs
You just need to reach Castle Age, which means you can build Monasteries, which can train Monks, and it is Monks that can pick up relics and store them in the Monastery.
yes
Choose the Persians as your civilization, and build a castle. From the castle you are able to train elephants in exchange for food and Save gold.
you can drop oil from towers in age of mytholiges but you cant in age of empires 2 unless it was a mod from "Age of Kings heaven"