We just bought a home built in 2000 located in a summertime humid
climate. We used to live in a dry climate where water damage was
pretty much unheard of.

It looks to be about ready for paint, and the front covered porch
floor is rotting in several spots, so that needs work. Also, some of
the siding where the planks butt together look like they should be
caulked, and maybe some caulking around the exterior of the window.
And there are some leaks in the gutters and some of the facia board
(the finished edge of the roof?) looks to be black/rotting.

Overall it's in great shape, but in need of some 8+ year
maintenance.

What else do I need to look for? What are the solutions to these?
When/where and how do I do the caulking?

Looking for basic problem identification and resolution.