If I am just playing around hunting elk for the first 20 hours of the game staying in Riverwood, will quests be waiting for me already bugged, NPC's dead or missing, etc.?
Or do I actually have to DO something to make these things happen, or enter certain zones for example?
Please advise. Anyone!
Most NPCs related to major quests are set as essential, so they can't die. I wouldn't worry about it too much.
The only really major thing you should know: If an old mage in the North sends you to fill a cube, and you have to use a machine to do that,
Spoiler don't grab the item you might find in the machine, unless you have the quest for that too.
That'll break the Main Quest.
I've seen one quest broken by waiting too long so far in about 350 hours of play with 3 different characters. A dog needed for a quest disappeared after I'd avoided him intentionally for 80 hours or so.