I keep having an issue when I enter a new area I have to select each person individually and move them through. How do I select everyone to move?

I don't know if there's another way but if everyone's standing close enough together, you can click and drag their portraits together so that they're linked and they'll all follow the character you have currently selected.

I don't think you can, try to drag your mouse over all but likely won't work.
What you can do though is drag their portrait card (which is bottom left at scxreen) on top of each other to group them, and while they are in a group they follow the selected character.
To separate 1 or each, just drag the portrait card ^ a bit away, repeat with each.

If you look closely when you click and drag one portrait across a chain appears - not always but you’ll start to see it if you look - I just drag one character to the front or back and that generally works most times

So no option to drag the mouse over the screen and select all characters like that?

a bit of a shame as this is used in a lot of other games and most people are accustomed to this I think

If you have one character in stealth, your companions will not follow unless they're also in stealth. Generally, as long as your party remains linked, they always follow.

This, I hate.

Sometimes I want to move one character one way and the party another. It's complicated and clunky here.

Yeah or if you have to jump across a broken bridge. Would ne nice to select the entire group, instead of manually jump with each of them.

Come on, it's just dragging the character out a bit to unchain it. Is it so painful?

It is quite painful actually, chaining / unchaining them is awkward and it takes more time than just having the standard select / select all.
I really wish we had this possibility, it could be as simple as an option to chose the "chains" or the normal system.