This time it didn't, will it attack my dwarves when any enemy attacks next time, or is it really tame this time?
Simple answer: If you caught it before he killed any dwarves, then he will be tame.
Any animal that has tasted dwarven blood can never be truly tamed - Which I expect was the case with your first hydra.
are dungeon masters still bugged, if so how do i set all animals to non-exotic
Yes, they're still bugged.
To make all pets non-exotic, you have to be prepared to do a lot of RAWs editing. Navigate to the RAWs folder in the Dwarf Fortress directory (DwarfFortress --> raw --> objects) and open up every single .txt file that begins with the word creature.
Then, search for every tag that says [PET_EXOTIC] and replace it with [PET]. The square brackets are important!
Then save and generate up a new world.
Actually you don't need to generate a new world, just change the raws on the world save folder directly.
Also you can use this wonderful program called
handy file tool, it allows to replace text in several text files at once, it's really a life saver for me in many occasions, in this case what would have taken at least 20 minutes to do took but a couple of seconds, it can also find text in several files in case you want to change just an specific creature.
Now for my first question of today, I read that you can influence where trade caravans spawn with paved roads connected to a depot, does it have to be completely connected without any gaps at all? because in my case the road would have to go through a couple of bridges before getting to the depot.