Jen,
The pork is just for the taste, usually I don take too becos after boil the soup, the meat will be tasteless. I prefer those soft bone pork ribs, nicer...
As for slow cooker, I got one with low, high and auto switch one, I find it quite convenient, like last sunday I boiled black chicken soup, I just switch to auto and start boiled it at 11am and do my ironing, tidy up my wardrobe etc, by 3pm or 4pm, the soup is ready. No need to worry my kitchen will burn..