What ever time you estimate, estimate more. I'd also advise to rest the pork butt for two hours in a cooler wrapped in foil and towels (allows the juices to redistribute). Buy yourself a good wifi temperature probe, this is a must. Never cook to time, cook to temp. Pork butts should cook until about 200-205 internal. Brisket I have not tried. I never sauce, only rub with mustard first and then various spices, can even just use a mccormick rub. Either wood should work. A 7lb pork butt at 225-250 usually takes me around 9 hours in the smoker. I'm not sure how that will change with more meat in there. I don't actually have an electric one so I can't help you there, but the rest of these methods are for any kind.
This is the thermometer I use