I am not sure how ubuntu works but would "apt-get update && apt-get upgrade" not update your installation to latest update from ubuntu?
I never used ubuntu so i can't confirm this. I know with ArchLinuxArm doing "pacman -Syu" will update your system to current state in repository.
Regarding Mali drivers, well this is question for Amlogic. They produce this GPU so they should provide mainline driver for it. There is effort to get this Mali in Mainline from Martin Blumenstingl and baylibre developers  and other around which I don't know but do upstream, also check  what their main guy, Neil Armstrong has posted on this forum. Also check  what @Gouwa wrote here. Neil also asked hardkernel for cooperation  as they also don't have mainline Mali support.
Khadas Support can request support from Amlogic. There was  "Voices from the open source communities will be passed to Amlogic" but I never seen public replay.
PS: This isn't place for such discussion so @Gouwa should split this to new topic.
PPS: you bought developer board not finished product. So a bit work from everyone is neede.
But I hope myself soon to have GPU support and use Kodi (without Xorg) with GPU acceleration when playing movies etc.