I'll let the food safety and sausage experts answer your sausage questions.
As far as the rest.
You want a temperature of about 225 - 250 degrees for the should ribs and brisket. Depending on the type of ribs, spares, baby back, etc it can average around 5-6 hours at the temperature. It's hard to check internal temps for ribs so the way I check for doneness is to lift the rack in the middle with some long tongs and if they bend about 90 degrees they are done.
Pork should has a lot of internal fat so it would be hard to approximate a time. Cook to temperature not to time. You want an internal temperature of about 195 - 205 degrees if you are making pulled pork, lower if you plan on slicing it. If you don't own one get a good thermometer that you can keep in the meat and give you a readout displayed outside the smoker. The temperature of the meat will frequently stall around 150 - 170 degrees and that can really affect the "how long" do I cook this thing. Be patient and you will be rewarded.
Brisket you can cook to a lower temperature since it's beef.
Dry rubs are always good on shoulders and ribs. Works great on brisket too. Try and experiment with different kinds.
Chunks will probably be better but you can use chips, you will just be replenishing them more often. Remember you want a thin blue smoke, not a white thick billowy smoking coming out of the stack.
Mop sounds good as well.
You have a lot of good ideas. Sounds like you are on your way! Good luck and let us know how you made out.
Welcome to the SMF!
Ron