Is Craft's Search case-insensitive?
(And is there a way to toggle case-sensitivity on/off?)
It depends on the underlying MySQL collation of the database and the tables Craft is searching against. The MySQL 5.1 rules surrounding this can be found here: https://dev.mysql.com/doc/refman/5.1/en/case-sensitivity.html
There isn't anything in Craft where you can toggle the case sensitivity of searches.
Turns out I was completely wrong on this. Case sensitive searches would rely on the database's underlying collation if Craft didn't normalize all search keywords to lowercase first.