There is a button somewhere (I can't recall where exactly, but it's there!) that foces all units in the city outside.

I think it's maybe an button on the action panel for the unit.  Sorry I can't be more specific, but I don't have the game in front of me.  It's something like "Evict" or something like that.  I had the same issue and found the button last night in the late hours.

As for healing, It appears that they heal for 5 points per turn that they are in your city.  Not sure if they heal out in the wilds.

You can shift select one by one each unit in your city you want to have in a group and then click outside the city to form the party there.

With the City Selected the "V" hot key has all units leave a city.

As best as I can see, units heal ONLY in a city??!!   I tried leaving them for a turn at an inn, but no healing.

Certainly an interesting design decision.

I think as long as your units don't move they'll heal, or maybe it has to be in your territory.  Whatever it is, it sucks IMO.

Your units and sov heal slower than it takes your civilization to research, learn spells, build buildings/units, etc.  It's kinda silly.

If you use any magic to heal your units then you'll be sitting around clicking to regain mana at 1pt/turn which is no better or is even worse.

What about hotkeys for groups? Can you have groups like in most RTSs? Ctrl+1 Ctrl+2 etc