[@Xaltwind]
Primarily you are free to do whatever you want whether it’s by yourself or in a group. Some side quests are related to the main story while some are just completely unrelated. I will never fast track players to catch up to the plot of the game. It’s more like once players reach a certain benchmark I may throw in some plot that involves everyone. However there are many avenues where you may just stumble into the main plot by accident too. 

There is nothing stopping you from going to various locations. It’s almost all entirely open.