Yes, ith, a collie could do all that. If you've a neighbour trains 'em and would let you work your dog on his sheep, plus the occasional light work on your own Soays, then I wouldn't have qualms about you having a collie.
Some working farm dogs are house dogs. They do focus on their work better if they're not - but unless you have 00s or 000s of sheep, or want to compete at a high level, you don't really need that level of focus. And unless they'll be working outside for hours upon hours in all weathers, being a bit 'soft' from living indoors won't hurt.
And yes, you can work primitives with a dog. It takes a very calm steady unpressured approach, so I'd recommend training your collie on your neighbour's sheep and only start to work the Soays once s/he's good and settled.
I drove the Castlemilk Moorit wethers with the dogs, but you have to keep the dogs way back and very calm. I spent many weeks just getting the sheep used to there being dogs in the field with them, then more weeks getting the dogs closer and lying down nearer to the sheep as they ate. So by the time I needed to drive the sheep, they were used to the dogs and weren't scared of them - aware and a little apprehensive, so they'd move away from the dogs, but not running, boinging, jumping all the dykes scared!