Definitive answer about "Event" Subject line please.

There are lots of threads answering parts of this question but I would like to try and get a definitive answer on the changeability of the "Subject" line in the "Event Module" please.

Can I change the "required status" of the Subject field or change the state of the Subject field to be a drop-down or another type of field? I dont mind at all the required status but I would like to be able to use a more specific indicator of the type of event other than plain "Subject."?

Thanks you!