A lot of people do this, so yes, it will work. The juice is normally already blended from a selection of apples from the orchard, so you don't have to worry about mixing...unless you don't like what the've done The biggest reason people do this, is because they can't crush the apples on their own.
Boiling your cider is ok, and because you're a brewer you should have a pot large enough to do it. I would advise 5.5-6.0 gallons though. In my experience using pressed apples over apple juice, is that you get a lot more sediment when you're done fermenting because the apple particles sink and bind to the lees, and also form a ring on top, around the fermenting bucket. Granted, it's not half a gallon's worth but when making cider...you just have to drink some now and then. When using cider pressed from an orchard, I would also recommend using a secondary.
Boiling is definitely harder than adding campden though.