extreme single-side tire wear and suspension questions

It's not likely that all of that is bad, but it is conceivable that the lower ball joints are hammered out of it (typically right side goes first). Replacing a ball joint (upper or lower) means the coil spring has to come out, so whole thing has to come apart anyway. They probably figured they'd replace everything while they're in there. Parts aren't really that expensive - I'm surprised they got up to $5k even with labor. Seems at least double what I would consider reasonable.