Just to intro, I am getting ready to start my baby on avacado on 8/17 (just after his 5 month bday) He has been on rice cereal for 1 week and started oatmeal this week. I am going to try a new cereal next week and then avacado the following.
About your beans, if you are going to cook beans in the slow cooker you have to boil them for about 10 minutes first. I saw this on food network. They didnt really explain why. I think it was on paula deans show.
I did find this link...
http://www.centralbean.com/cooking.html#How%20To%20Cook%20Dried
it explains several different cooking methods and details the problem with slow cookers (citing the hard water can also cause problems).