I get the same issue, frame rates are fine yet for some reason the output stutters constantly. I hope this is something that will be fixed in a driver update.
I have a similar setup (but only a PhenomII X3 710), but haven't yet tried CS:GO on it. I don't have the stutter problem, but I do get random infrequent complete freezes with this driver under Ubuntu, but not with the latest drivers in Win10 on the same hardware.
Your dpkg output says that the desired state of the amdgpu-pro package is to be "installed", and that the current status is indeed "installed", and that there are no errors with the installation. The extra output you refer to is merely an explanation key with a bit of ASCII art to point to the relevant indicator columns.
You can check /var/log/Xorg.0.log to check that the modules are loaded from the amdgpu-pro directories and that there are no errors there.
Your "lspci -d ::0300 -k" output will list your GPU(s) and the modules used for them - mine shows:
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Device 67df (rev c7)
Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Device 0b37
Kernel driver in use: amdgpu
Kernel modules: amdgpu