Yours probably came from the factory with Dot 3 brake fluid which is suitable for your drum/disc brake setup. If you are worried about the brakes getting high usage (heavy regular braking that might cause excessive heat in your components) then you might consider upgrading to Dot 4 which from what I recall is meant to withstand higher temps. Since they are compatible fluids, no need to completely flush the systems unless your concerned about debris or contaminants.
Everything I've read says DON'T use Dot 5 unless your equipment and operation demand that. The fluid is silicone based, which is not compatible with nor will it mix with Dot 3 and 4 fluids. Switching to Dot 5 requires complete flushing of the brake systems as well as replacement of some components that flushing the system can't completely remove the Dot 3 or 4 fluids completely. My understanding is it's very costly and unnecessary for regular vehicles usage.
Merry Christmas back at you!
