Can I shorten bean soaking time if they'll be slow cooked?
I use a slow cooker almost every time I cook dried beans, and I don't recommend cutting down on soaking.  I typically soak overnight (with a little bicarbonate of soda), and start cooking in the morning, so 10-12 hours soaking + 8-12 hours cooking, avoiding adding (much) acid/salt until towards the end.
It's possible your beans soften more easily than mine,  but with a much shorter soak (say 4 hours, and 10 hours cooking, because I forgot to soak them overnight) I've found several types to be barely edible - I ended up cooking down my chilli , blending it, and eating it as bean burgers.