If you've not yet read about the general changes in the 1.4 beta line, now is a good time to do so. It's expected that we'll stay in beta for the new features until we release the 2.0 version of the game in late August, alongside the new Nihon no Mura expansion. A lot is different in the base game since 1.4, so we want to make sure and give this time to mature before we put this out to everyone.
This one just more last-minute tuning prior to the upcoming 2.0 release. There was one exploit with cultural victories, but aside from that nothing serious. Things are looking good!
This release is the fourth "release candidate," which basically means we're into fine-tuning-only mode until this launches this week. Probably Wednesday, but we'll keep you posted!
This is a standard update that you can download through the in-game updater itself, if you already have any version of the game. When you launch the game, you'll see the notice of the update having been found if you're connected to the Internet at the time.