Closed Update

Steam should update it by itself. Also the version shown in the launcher isn't the actual game version. When you start starbound you have the version in the right bottom corner when you're in the main menu.

~ Iris ~

 

It's not a bug imo. Afaik the launcher access a webpage on the starbound server itself and this one must be updated. But i don't think that they'll do it until development is finished.

~ Iris ~

Edit:

for the stable branch update 3 is the latest version.
All other things since then were implemented in the nightly builds.

 

You have in your steam library starbound - unstable. There you can select nightly in the beta tab. The unstable/nightly data will be stored independent from the stable version so you won't loose any progress there for now.

~ Iris ~

 

Nightly builds are updated most often, but are subject to game-breaking issues given that it's mostly intended for sneak-peeks and beta testing. Content is eventually bundled into the Unstable build, where it's then pushed to Stable for proper play.

So, all new things do reach Stable eventually. But getting in early with Nightly does come at a cost, so you should know what you're in for before making the switch.

 

Mods will be mostly incompatible with the nightly because most mod authors don't update them to nightly. But your character files, universe files and yes even mods are independent if you are using them in stable. Nightly is a standalone installation with it's own folder.
But like @Jonesy already said it does come at a cost.

~ Iris ~