Don't give up on finding buckets... Keep checking Craigslist, and check surrounding cities, as far as you're willing to travel to get one. Even a search on Ebay, within a certain mileage radius. Some may actually find you... A buddy of mine asked me last summer if I'd be interested in a 12" and 24" for my Case. Nothing wrong with the 12", and the 24" needs a new bottom. I asked how much, and he said $50.00... I asked each..?? He said for both, or he was going to scrap them... He has a Ford hoe, so no use to him. I gave him $60.00, and we were both happy...
As for the two holes. The lower hole will allow the bucket to rotate back far enough, if you want to like sheer straight down a wall, straight behind you, without extending the boom & stick all the way. The other will let you curl up closer to the boom, probably for looser material, and clinch things against the stick, if needed.