First off, the posability is topnotch for the upper body - a joint at the midsection and standard HGUC armo joints make sure of that. However, the legs are a bit more problematic. This isn't just a historical issue, but also one where the new lower legs are really by nature more limited in standing poses. The best solution would be to keep on some sort of stand, since it's meant to be a space unit anyway.
This is me trying to imitate a classic illustration/MSV pose.
The backpack is very detailed, but be warned, all white parts and the red hexagon are stickers. This unit will definitely teach you to get better at basic masking.
I'm not sure if it's possible, but I think you can mount two bazookas into the weapons mount, barring any fit issues with the sensors and handgrips, when they're folded down.