Welcome to SMF! I see it is your first post here. If you would swing by role call to introduce yourself and add your location to your profile, this way you can get a proper welcome and in future questions things can be specified to your location if needed.
OK so on to your questions........
First thing is relax. This will be a long process for making Pulled Pork. If you cook at 225 degrees you are looking at 1.5 - 2 hrs per pound. I plan on the 2 hours. Not all meat will cook the same, so it will be done when it is done. If you get to a point where you can not tend the fire or need to speed up the process a bit, you can do the final foiling step in an oven if needed. the meat will not take any smoke when foiled.
Charcoal: I use a chimney to light about 10 coals. I will make a "C" in the charcoal pan and place a few chunks of wood along the "C". When the coal are glowing I place them at one end of the "C", making sure it is not touching the other end of the "C". This is a method I saw here and tried it and it works great. Open the top vent all the way and use the bottom vents to adjust the air to the fire to control your temperature. This helps keep the charcoal out of the ash and maintain a more even cooking temperature.
Water Pan: That is a personal choice on weather you use water in it or not. Some love it and others do not. I personally use a dry chamber and do not mop/spritz my meats as they cook. I would add some clean playground sand to your water pan (about 3" worth). I then would form a valley in the middle of the sand and line this area with foil to catch the juices and keep the sand clean for future uses. The sand will form a heat sync that will help even and maintain better temperatures.
Food: as stated a Maverick is great and I love mine. If you do not have time and need one now, try some of the Big Box stores like Lowes, Home Depot or even Walmart. Where they have the grills they will have a single probe version for about $25-$35. Make sure you calibrate it in boiling water. It should read 212. If not make a note of how far it is off and keep that in mind when checking the temps. If your on a tighter budget you can get a pocket thermometer from Walmart or Target in the cooking supplies area. They are about $10-$15. I prefer digital, they seem to be more accurate and less chance if dropped of losing their calibration like a dial style will. Just remember if your look-in you ain't cook-in and this will add time to your cook because of the temp recovery.
Cook Chamber: Again Maverick style is best, but you can use the one that came with your smoker. Just check to make sure it is calibrated, most that are stock are way off. You can add others to your smoker, but I would go with a remote sensor style. this way you know what the temp is at the grate level for the meat. Your will tell you the temp at the top of the smoker where the probe is. You will still be able to smoke and get great results.
Rubs: There are a ton on this site and others. As suggested if you are getting head spins with all the info, maybe use a store bought one to start with. Then move into making your own. But if you are wanting to tray your hand at it here is mine and a link to some of my cooks.
This is the rub recipe I am using at this time for all of my pork. It is a sweet rub with a good balance of flavors.
1c Sugar in the Raw
1/4c Fine Ground Sea Salt
4 1/2tsp Granulated Garlic
4 1/2tsp Course Onion Powder
2 1/4tsp Celery Salt
1 1/2tsp Ground Oregano
4 1/2tsp Chili Powder
4 1/2tsp Fine Ground Black Pepper
For some heat I would add 1tsp smoked chipotle powder. The boss does not like spicy food so I don't at home.
This is enough for 2-3 butts or 2 shoulders or 6 racks of SL rib racks. Will vary on size and how much you apply.
Mix all ingredients well and rub onto the meat generously..
Here are some links of it being used:
This is the link to the foil/finishing sauce I use...