"1. I bought the Nomex gasket to seal the smoker and fire box, but keep thinking it might be easier to use a caulk type substance. I thought I'd seen some instructions where someone had used Rutland High Temp Sealant or Gasket Maker or something and I think they said they'd put a bead around then put a thin strip of wax paper on top of it and closed the lid to flatten. Is that as effective as the Nomex and how exactly would I do that. Also, where can I get the material to do that if it works well? that sounds easier to me than the Nomex and I'm thinking might be significantly cheaper. I was also worried about the sealant sticking to the lid and basically glueing it shut. If someone could give me some details (and even maybe pics) that would be a great help."
You can use the Rutland brand, myself I was too cheap to spend that much cash, I went to WalMart's auto dept and got a tube of high temp gasket seal, ran a bead around the lid then placed my stove rope on that. I closed the lid put some weight on it and left it like that for several hours to make sure it was good and dry, it has worked perfectly so far.
"2. You mention the disposable aluminum pan. I'd read about the deflector plate and was concerned about the cost of it as well as a permanence of it as I plan to use the charcoal grill aspect of this as well as learning to smoke. With the disposable aluminum pan it doesn't sound like it'd be expensive and maybe wouldn't take much to put it in and take it out. How exactly did you do this and can you just quickly and easily pop it out? Has it made a pretty significant difference? Any pics?"
I saw pics of the more permanent style on some ones blog on here I believe, but like you I may want to use the charcoal side sometime so I did not want to permanently attach something that would prevent that. I just cut the corners so I could flatten the pan out, stuck part of it through the hole into the fire box and bent it so it would hold, then did the same tot he under side of the charcoal rack (which I have raised all the way to the top) it was not difficult and seems to work great plus I buy 50 of those pans at a time at Sam's Club because I do a lot of cooking and they are handy to have around so they are less than $.25 each that way I think, so if I mess one up taking it out I will just make another. I am about to put a 10lb pork butt on this morning for some pulled pork, I will see if I can get some pics that will turn out before I get it started.
As for your question #3, I have a couple spots that leaks very small amounts of smoke but so little I am not going to concern myself with them at this point, I think it is grill specific, depends on how drunk the welder was the night before he welded your grill. Mine must have stayed home the night before he made my grill :)
"4. Do I need to seal the firebox and if so what do I need to seal? I've read that you need to and also that you shouldn't as it cuts back on airflow and am a bit confused. Opinions?"
I sealed my lid just like I did to the smoker box with stove rope and high temp auto gasket sealer, other than that I left the rest alone, you will find that raising your charcoal grate in the fire box up on a couple bricks will allow more air flow, as for the bricks in the smoker side I am not sure if there is a ton of benefit but they have to help hold a little heat and in my small mind holding any heat is a good thing and I had the bricks so why not.