Ron - We've got our Pro Q 20's pretty well dialed in at this point. Here is what we do.
1a) For a longer cook (butts, brisket) we load up the entire basket almost full to the top with unlit Bluebag K. We then hollow out the middle as best we can. There will be unlit K above the top of the basket around the sides of the hollowed-out middle. We then place a full Weber chimney of lit K coals into the hollowed-out middle. We then use the chimney to actually mold the shape of the lit and unlit K coals into an even mound (it is kind of an intricate process). We then add our cooking wood, usually 3-4 chunks depending on size.
Next we add a foiled water pan and fill it up about 1/3 of the way with the hottest water you can get your hands on. We use boiling water or if we're feeling lazy we use the hottest tap water we can find. We let everything settle for about 5-10 minutes and then the butts or briskeys go on. Temps for us are usually right around the 225-240 mark at the start. We will then adjust vents accordingly to get to our optimum temp.
1b) For a mid-range cook time (ribs) we basically do almost the same thing. We will reduce the unlit K coals to about 3/4 of a basket and add about 3/4 lit chimney using the same hollowed-out (MM) method). We add wood the same way and tend to use less water in the foiled water pan, but still make sure the H2O is hot. Temps for this cook also mimic the longer cook for us.
1c) For a fast cook (chx) we will line the bottom of the charcoal basket with unlit. We then drop a fully lit, overflowing chimney of coals into the basket and spread them around evenly. We then add our wood and put on a foiled water pan. We do not add any water for this cook at all.
2) Of the few times that we have had trouble getting the temps up, we have taken out the water pan, ditched the water in the pan, and returned the pan to the smoker. This has always allowed the temps to come up, and in some cases higher than we wanted.
I think the key to using water is to use hot water. I really believe this. It is really more of a scientific thing than anything else really. If you use cold water in the pan, the coals (fuel) will need to use more energy to get that water hot....energy that would be better used to cook your food and maintain a consistent temp.
3) Lump has always cooked hotter in my opinion. I dint like using it, because I have too much trouble controlling the temperature spikes. Some people swear by it because, hey, it works great for them. I myself have just gotten use to the consistency that the standard Bluebag K offers me.
I can say one positive thing about lump though. I have only cooked using the Ono brand of lump once. It was the first lump that I have used that I have actually really liked. I didn't use it on purpose, but because it what was given to me to cook a bachelor party. For that cook, I used one 20 lb bag of Ono for the entire cook and also used the third Excel 20 stacker for the first time. If I was to ever use the third stacker again for a cook, it would be with the Ono brand of lump. Good stuff and you can get it from our club sponsor BBQ Island.
4) The lid-mounted thermometer just really isn't going to tell you what's going on temp-wise two levels down. I can see the pros for it if you are hanging something by the hooks up top, but even that would be sketchy at best. We like to use the Maverick E-73's at each grate level to get an accurate reading.
Mark - You had asked about the differences between the Pro Q and the WSM.
1) Pro Q has a hanging bar and meat hooks for a vertical cook.
2) Pro Q has eyelets at each grate level that allows a thermometer to probe the temp at each level.
3) Each Pro Q stacker (section) has handles on each side to allow for easy access.
4) Water pan on the Pro Q is much bigger than the older WSM's (I have no idea how big the newer WSM water pans are)
5) Pro Q has latches that allow you to access one level without having to remove grates.
6) The WSM is much more popular and has won a lot more awards than the Pro Q.
The WSM and the Pro Q are very similar cookers, but the Pro Q definitely has more features. An overwhelming number of Excel 20 users love the cooker. I know we enjoy cooking on our Pro Q's much more than on our WSM. Of all of my contacts with Pro Q users, I have only heard of one person that did not like the product.
Hope that helps. If you have any other questions, post them up and someone will surely get back to you.