1. I am totally against horses living in a stall HOWEVER I live in NZ where the climate is mild so everything is done out in the paddock. I realise that some of you are dealing with bloody awful climate conditions - heavy snow etc so I am not the one to ask about this but my gut instinct is always to look to the wild...if your weather is not too bad around foaling then leave her out in the paddock - she will choose her own 'nesting spot' (yes they do) and she chooses around a week before she foals.
2. Regarding separation, if she is in a herd environment with mares she does not need to be separated - as long as you have a big enough paddock and she can get away from the others, she will be happier left with them however (there's that word again) if you have an annoying busy-body gelding (like I did) then separation may be necessary at least a week or two before foaling but only to a next door paddock so they can still touch and see each other over the fence. Always remember horses are HERD animals and herd animals MUST HAVE the company of other members of their herd in order to feel safe and comfortable.
3. Last point (I promise) - God how I love to lecture Weaning - once again I believe that weaning should not be done before 9 months - again look to the wild - they're not weaned until just before the next foal is born. It's not just about milk but about learning to be a horse. My favourite article on this is here (Scroll down to progressive weaning)
Natural Horse World Articles-Foals
I think this woman is great.
Do NOT get talked into weaning earlier UNLESS there are major problems with the mares ability to care for her foal.
All and all it sounds like you know what to do and good for you - shtick to your gunsh