Good luck with your new horse. I'd do exactly what you've already got planned - vet, vaccinations, teeth, farrier etc and take your vets advice on what to vaccinate for and if your mare is in foal, start her on good nutrition right away.
I knew nothing about horses/foals at all - but when my son was left with a pregnant mare, we all learned pretty quick.
I'm in the UK so horse breeds, medicines, vaccinations, food etc is different over here to a lot of things I read about on this site, but the advice and support can be invaluable - there's always somebody who's been there and done that and can offer a word of encouragement.
Our magic feed was sugarbeet in putting weight on our pregnant TB. Despite the best of everything, she was notoriously difficult to get any weight on and that was our saviour. We mix it with chop, stud mix to help with her milk (vets advice) and she has a full vitamin powder supplement in it as well as garlic powder, and apple and carrots (and my dad always put a mint in the bottom lol). As well as unlimited haylage and she's gone from strength to strength (and to deliver a beautiful colt last Thursday who's just perfect).
We had a shelter similar to the first (but not as posh lol) which had a flag floor - laid straight onto the grass. This had been there for years and was bone dry until last summer when we've had such dreadful we weather. The flags lifted and we couldn't keep the wet out, so we've ended up concreting the floor and now it's perfect. Dry and warm when the door's shut - the little colt was fast asleep when I went down an hour ago - bedded on a foot of shavings haha. So from experience, I would have a solid floor if you can - for warmth and comfort. Ours hasn't yet ventured outside as it's just too wet and the field too boggy - hopefully it'll be drier weather this weekend and we can roll the field - something else to think about (depending on your land).
If she is in foal, i'd start these preperations asap if finances allow - we started later than I would have liked and have still to make the ground outside the stable solid (it's ok now, but not as I wan't it to be).
And despite having a lovely relationship with Fox, the day after she foaled, whe turned into a monster mummy - that's wearing off now - I was able to muck out half of her stable this morning without her pinning her ears back - but prepare for the protective mare instinct to kick in after delivering - that surprised my husband the most (Fox adores him) - I think he was shocked when she kicked out at him at the weekend - I've just been keeping out of there - who's the clever one now
Haven't a clue about paint/frame etc so i'll leave that to the experts x
Good luck and keep up posted - we're an impatient lot!