:hugs Sorry about your bad day. Life throws them at us all sometimes. Can't do much but get through them and know that it does get better again. I hope the hurt quail recovers.
WAG* between 500 and 5000 - it depends on a lot of things.
What part of the county are you in? Will you be boarding or keeping it at home? Trail riding, doing any showing, 4H, etc?
It will nearly always take more money than you thought - especially if you have an emergency vet call or two...
It's likely as they get more pasture, they'll eat less hay. I try to feed mine enough that they don't leave much each day (because hay a day old is not nearly as good as hay freshly put into the feeder! lol). If they left some, feed a bit less next day. You'll get to know your sheep and how...
The basic vaccination for sheep and goats is usually CD-T, which is the only vaccine I do. Lambs get two vaccines a few weeks apart, adults get one yearly (most give it to ewes 30 days or so before lambing, so the lamb gets antibodies in the milk). I'm going to copy from a website, Sheep 201...
I've never separated my lambs (by the time they go to the processor, they're not really nursing anymore), so I'm not sure exactly how long it would take. I'm guessing a week might not be long enough. Hopefully someone who has done it can tell you what works for them.
Congrats on your sheep! Yes, any feed changes should be done slowly. Back down on the grain as they get more pasture. Start with about the amount they were getting at the place you got them. If they stop gaining weight, or start losing it, increase the grain slowly again. Can you separate...
I think you've done great with them, getting them at a few days old and no experience with lambs!
Have you started them on their vaccinations yet? And read all you can on parasites, especially internal ones. Sheep (and goats) tend to have more problems with worm resistance than other...