So it sounds like I definitely want space between the rocks and the top grate?

Yes, you want space - 2 inches would be good, more would be better. You can also look at ceramic briquettes - they have a lower profile https://www.amazon.com/GrillPro-43118-Ultimate-Briquettes/dp/B002FYAJ7I/ref=sr_1_4?ie=UTF8&qid=1473980383&sr=8-4&keywords=bbq+ceramic+briquettes https://www.amazon.com/DUCANE-Gas-Grill-Ceramic-Briquettes/dp/B00DX617V4/ref=sr_1_6?ie=UTF8&qid=1473980383&sr=8-6&keywords=bbq+ceramic+briquettes . I haven't researched those particular items, but I have used ceramic in the past, and prefer them over lava rocks, because they are a uniform size and are easy to stack in a single layer and get even coverage - the lava rocks are different sizes, and so it was common that stack them a bit so they overlap.

Found a basic 7lb bag of lava rocks just to get things started. I was pretty surprised to find that the bag barely covered the bottom grate. Of course, there is a big enough gap on either side between grill and grate that a few fell down to the fire. Started the gas and lit it. While lit, I turned both sides to high and was disappointed that the flames barely reached the rocks. Guessing that's just where the heat from the rocks will come in after 10-15 minutes of pre heat time. I'm just used to seeing flames up closer than that!

That's correct with the lava rocks your cooking with indirect heat. This just means that your using the flames to heat the lava rocks and not cooking with direct flame. It's supposed to help by disbursing the heat and keeping a more even temperature throughout, but everyone has their own personal preferences when it comes to grilling. Indirect additionally is said to help with flare-ups while grilling since the grease and oil drops down onto the rocks instead of directly on the flames; but from my experience it just depends on what your cooking. Grilling anything with high fat content or using a lot of oil in your cooking will generally give you some flare-up regardless.

Best way to tell when to start cooking is just to use the temperature gauge on the grill if you have one.

The temperature gauge is actually broken, of course. This grill seems to be closer to an over given the distance between grates. I'm building a fire pit in the backyard next year anyway (good setting and I didn't know this one still worked). It would have just been nice for a quick dinner grill.

You can always use the hand test for cooking temperature, hold your hand a few inches over the grates and depending on how long you can leave your hand there should give you a good read on temperature.

High (450° to 550°F): 2 to 4 seconds

Medium (350° to 450°F): 5 to 7 seconds

Low (250° to 350°F): 8 to 10 seconds

Let me know if you have any questions regarding the fire pit. We do have a few different lines of Fire pits/ Fire tables on our website both gas & wood burning.

I might try that...the last time I tried anything on the grill, I had the two sides turned on high for 20 minutes to pre heat and then the sandwich I was cooking took at least 30 minutes. Mind you, it was fantastic and tasted better than my usual stove top. It just isn't worth an hour of prep and cook time.

I'll keep you in mind for the fire pit, but I'm currently planning to build it with retaining wall bricks.