2 things:
First, I am playing with diseases on, and I find them to add some fun flavor. Namely, a completely unique threat to fortress stability. I had flu sweep through everyone as I was setting up the hospital and spent 2 seasons just trying to get that sorted out. I also had meningitis start, but thankfully my med production was up to snuff that time. I handle them by constantly producing medicine, so that my stocks of drink are half meds. That way dwarves are taking meds a good portion of the time. I do nothing with special stockpiles, or burrows, or micromanagement. It just means that my drink production takes alot more plants, making me dependent upon caravans getting through at least once every year or so. So I enjoy the addition of diseases, and find them not to be too strong. I can handle almost any invaders, and am still setting up industries, and they add a low level threat that I have to keep balanced without demanding an annoying part of my attention.
Secondly, I need help with the magic altars. I am trying to setup an area with all of the altars, but I am confused as to what exactly I need. The only option I have to research is magicka but it says I need a specific discovery for each altar. What am I missing? The manual still says its one good, one bad, and one elemental altar, but the building menu seems to have an altar for each element. Help would be appreciated, I think I am just missing something simple.