Where can I find information about how modern psychiatric hospitals
for the criminally insane are run? I would like to know things like
the physical structure of the hospital, the types of treatment, the
admissions process, regulations and procedures, the release process,
and possibly case studies or first-hand experiences.

This might help:

http://www.orb.on.ca/english/legal/psych-hosp-guidelines.pdf
Guidelines of a psychiatric hospital in Ontario, CA.

And here, scroll down to "C" :
http://www.dir.ca.gov/DOSH/dosh_publications/hcworker.html

http://www.mhcva.on.ca/m1mhcp.htm