Dried beans can be a pain. Here are my tips: When soaking over night start them in hot water. Either bring the pot with the beans and water up to a boil then turn off and put in fridge, or heat up your kettle and pour the hot water over the beans and soak over night. My other suggestion is your crock pot. Soak over night, put in crock pot, come back in afternoon and they should be done with out much thinking.
You can cook the beans in the same liquid you soak them in, but some like to drain soaking liquid and start fresh. There's a few reasons. Draining the soaking liquid from the bean will lead to less gas and a less thick liquid around the bean. (If you want bean salad for example.) Cooking the beans in the soaking liquid will make the liquid thick. This is great for rice and bean dishes where you want almost a bean stew. If you do drain the soaking liquid you can save it and add it to soups and other times you would add broth. The same thickening effect may occur, depending on how much of the bean liquid you use.
Lentils are a little different. They don't need to be soaked. Make sure they have enough liquid though. I find that when they soak up all the liquid before finishing cooking, there is no bringing them back.
Hope that helps.