Rubs are all personal preference , find one you like and roll with it , there are handfuls of brands at grocery stores to get you started , as you get deeper into this you will learn more of what flavors you want and or don't want , etc.
I run my offset at 225 degrees and use mostly lump charcoal for heat ,
I only "smoke" with wood for the first couple hours with seasoned hickory , then it's straight charcoal til the end . I do this because "I" find it's the right balance of smoke for "my" taste , remember bbq is all personal preference.
I run the butt to 165 internal temp and then wrap in aluminum foil , again this is my method , some people don't wrap at all . When you wrap you can add more seasonings etc if you'd like and then it's back on the grill til it hits an internal temp of 192 , at this point I pull the butt off the grill and place in a cooler to let the meat rest , internal temp at the end of the total process should be at 195-200 to eat .
Then the best part , the bone should slide right out cleanly , and then do what you wish with the meat , some pull , some chop , some slice , it's all BBQ at the end of the day .
I'm no expert , just my process of how I do it , more will be along with their methods , take them all in to account and do what works for you .
Practice makes perfect , kinda ...