Getting Started

Better to be lucky than good any day.  Great score right there.  Welcome aboard and enjoy the journey.  Above all, have fun.
What follows is a collection of thoughts that may help you out:

Here’s a link to all things ceramic-chances are if you have a question the answer is within this site somewhere.  Check out the recipe section for some great ideas.  http://www.nakedwhiz.com/nwindex.htm

For additional links to cooking/recipe sites; here are two very good ones, depending what you are cooking:  This site contains a wealth of the science behind Q cooking along with info on about every type of meat cook you would attempt: http://amazingribs.com/

Here’s the second one:  http://playingwithfireandsmoke.blogspot.com/

 After-market toys- With the BGE there are three basic styles of cooking;  “direct”-where the cooking grid is on top of the fire ring; “raised direct”-where the grid is elevated at least to the gasket-line (this setup requires after-market stuff-easiest is to get another grid and then use three fire bricks (or three empty aluminum beer cans) and place them on the grid at the fire ring and then put the second grid on top. The third is “indirect” where there is a heat deflector (platesetter or some other type stone) between the burning lump and the cooking grid.  This is the setup for low&slow long duration cooks.  I would get comfortable playing around with the BGE before any major after-market investments.  Will save you $$ in the long run.

 Some observations-make sure you calibrate your dome thermo-boil some water, then insert the thermo and check the temp.  If not around 210*F, then note the off-set and use the nut on the back to correct.  Then recheck.

Temperature is a controlled by the volume of lump burning.  The volume is controlled by the air-flow thru the BGE.  In thru the bottom vent and out the top.  Make sure when you set it up that the fire box opening is aligned with the lower vent. 

When adjusting the vent(s) to change temperature, the feedback loop can take some time.  Changes in air-flow are reflected in the dome thermo temp.  Don’t chase temperature; +/- 10-15*F is close enough.

“Stable temperature” is a relative term.  Means you haven’t moved the vents and the temperature is steady for anywhere from 30-60 minutes.

That is likely more than you need to know.  The search function here will point you to many topic related threads as well. You can also use google and add egghead forum to your query.  

Very nice, it looks like your off to a good start. Please be aware that Royal Oak lump is the same as Big Green Egg lump, just in a different bag and a lot cheaper. EGG ON!

Congratulations, and welcome!  I am sure you will LOVE your Big Green Egg!  I cooked on other charcoal grills and a gas grill, and it was all fine, but I never really loved grilling and smoking until I got a Big Green Egg.  I LOVE it!

One more newbie suggestion:  Once in a while someone can't figure out why he can't get it very hot, and it's because he didn't put in enough lump.  As others said above, the air flow is what controls the temperature, so there's no reason to skimp on how much lump you put in, and putting in too little can be a problem.

I almost always fill it up to the top of the fire ring.  Then if it's for a low-and-slow, I'll light it in the center, and if it's for hot-and-fast grilling, I'll light it in 2 or 3 places so it can spread across the whole surface of the lump quicker.

Completely agree on taking it easy and enjoying it the way it is for a while without worrying about buying extra stuff.  Lots of guys are all about accessories and have a ball with tons of them, but I've been Egging for years with just my Eggs, plate setters (now called Conveggtors), and a good instant-read thermometer (Thermapen).  A remote thermometer that will tell you the temperature in the Egg and the internal temp of the meat is also something to think about getting at some point, but I wouldn't even get that anytime soon.  Just get used to the Egg and cooking with it.  You really don't need a lot of expensive additional stuff.  You can have all of that stuff if you would enjoy it!  But don't worry that you need it.

Have a ball!  And welcome!

Welcome!