Do any of the Main Quest involves picking a Faction (Imperial/Stormcloak)? Which Quest is it? I just want to know beforehand when starting that Quest so I can at least make up my mind first. With 25 hours in the game right now I still don't really much about what each Faction is all about.
play the game , read the books, talk to the npcs.. the civil war quest should be in your journal already, join imperial legion/stormcloak etc.good luck, Ave True to Caesar
So it is possible to complete the game (finish last Main Quest) without joining any Factions, right?
Yes, I did on my first playthrough and didn't have to join. Though im much happier with my second playthrough, the civil war was more interesting then the main quest for me so Im dong that first for this second playthrough.
Yes, but one caveat. Running the MQ and the Imperial/Stormcloak questline at the same time can screw up your game but good. So finish one before starting the other. In more detail
Spoiler
The MQ requires a truce unless the civil war is over. If you have already joined either faction (Imp/SC) the truce quest can become impossible to advance due to dialogue glitches. You need the Jarl of Whiterun's aid for the MQ, and unless the city is secure (war over or truce on), he will say "no."