Has the passing of time really any meaning in game, like an event occurring after x days, or can I spend literally weeks moving between 2 locations without any progression of the 'game world'...

Take as long as you like exploring. As far as I know only travelers like the traders move around. Other than that nothing else really changes with time. Most quest related NPC's will just wait forever untill you talk to them and activate the next stage.
There is one quest that comes to mind that is influenced by time. I'll put it in spoilers so I won't ruin your game experience, so don't read it if you don't want to know anything about future quests.

Sounds about right to me, and I don't think there are any pressures to complete stuff within a given timeframe overall.

However there are situations where timing is very important. Without wanting to spoil I hear it's possible to complete the ghoul Ten Penny quest and shoot em in the head quest but it requires you to do things quickly before the window of opportunity dissapears..... (I usually balls it up somehow though!)

The main things you will notice from the passing of time is Hostile settlements might calm down, traders re-stocking and some re-spawning enemies.

This. All vendors will re-stock, all enemies outside (and a couple indoor locations) will re-spawn every three days. If you piss off a town, leave and come back in three days, and they won't try to kill you. Otherwise do things at your own leisure, no matter how urgently NPCs ask you to help them, except for that one quest that trickksta mentioned. Depending on how fast you advance the main quest, determines how long this quest stays active for you.

there is one quest that does have a time thingy to deal with. and it is logical because they will die if you take too long to save them. and the last part of the main quest has a time thingy. but most of the game is open.

thanks for the detailed answers.