Some great advice here.
No-one's mentioned Barbara Sykes' book yet, so I will
Get a copy now and read it cover to cover!
Also I would recommend, if you can find a copy, John Cree's Problem Dog - he's an expert with GSDs and collies, an ex-police dog trainer, and the book is full of cracking ideas for dealing with problems - and would give you some insights to help with avoiding creating such problems in the first place!
Cannot agree strongly enough with the low protein diet - even my working dogs get limited protein unless it's a really busy time of year when they'll be doing long hard hours. TBH, unless they're gathering 00s on the hill day in day out they really don't need much. Tinned Chappie and a proper wholebake terrier meal for crunch is plenty for a pet collie; many farmers feed them maize meal with just the odd egg or tin when they're working hard. They are bred to scavenge on the job, though - so don't think that just because your collie is finding things to eat when you're out that it means you are underfeeding it.
And I also wholeheartedly agree that the collie should have a safe haven - a crate is ideal, or a den made under a table, for instance, but somewhere it knows it can go for peace and safety, and the children know they must leave it alone when it's in there.
(As an aside, I wish tourists could recognise that my collies regard the quad bike as their safe haven when I'm out working with them - if they have any worries at all, they retreat to the basket on the back of the bike. As we farm across several country lanes, I am very pleased about this. So why, oh why do tourists feel the need to approach them with their hands out towards them 
They're far too well-mannered to nip, so if they don't like the person or group of people, they have no choice but to disembark. Now I've got a stressed collie in amongst strangers and often on the side of a road... Surely these people wouldn't approach a dog in a car? Why do they think approaching a collie on a bike is ok? And I have to keep my own feelings under wraps, because if the dogs sense my own anger / frustration / concern, it would make them feel concerned or even that they need to protect me / the bike... Grrrrrrr!!!!!!)Would a Collie need a crate?
If things were busy, with say other children here, could I not just call her away to be with me like I would Alf. See, this is where I lack knowledge of the breed.
I like the intelligence/ activity of Collies. Only really "know" retrievers and would choose Flatties over the others because although they are harder work I find labs a bit boring 
. Sorry to go on, sort of thinking aloud and trying to gain Collie knowledge in order not to make a mistake. Oh, am I worrying too much .
Collies need 'down time' while they process what they've been learning. They are obsessive by nature. I would absolutely
not recommend that the only safe place your collie has is by your side - s/he would become completely fixated on you and distressed when you are not there. Much much better to give it space to be its own dog, and feel secure whatever else is or isn't going on elsewhere in the house.
And bless you for doing research and thinking hard about this.
Personally I don't think you are worrying too much, no - better by far to think it all through and ask advice
before you have a collie. Once you've got the dog, problems can evolve incredibly rapidly - so much better to be as armed as you can be in advance, and avoid as many problems as you can foresee.
Derek Scrimgeour says that with a collie, you should never ever tell it off for what you think it has just done or is doing. By the time you can react, it's already several thought processes ahead and thinking about its next or next but one move. It would process any reprimand in the context of what it's thinking - and you don't even know what that is!
I am completely convinced that this is behind a lot of the tricky problems that evolve with collies, working and non-working. You think you've told them off for A, but they think you've told them off for G and behave accordingly... Derek mostly doesn't reprimand the dog at all, he threatens the place he doesn't want the dog to be. For instance, if you think the dog will rush into the sheep and you don't want it to, Derek would literally shake a stick
at the ground between the collie and the sheep, while doing a gruff voice. Mostly the collie won't take the risk of crossing the 'naughty ground'; the instant it moves other than towards the sheep (in this instance), Derek will tell the dog what it's doing in a light and happy voice. (Usually 'Come Bye' or 'Away' as it moves around, not towards, the sheep.)
