Wow. I missed this.
I had a Trueleo with EGR on my car. The car was recently sold, however.
First...
If you have to get your car smogged, you want EGR. It'll be a PITA to get it to pass without it.
If you don't have to pass emissions, it's pretty much your call. If you delete or bypass the EGR, you should have it disabled in the programming.
When the EGR is commanded on, the ECM also throws in a bunch of spark advance and leans the fuel mixture waaay down.
Usually, that's a recipe for a bunch of ping (knock, spark rattle, whatever you want to call it.)
The introduction of the burned exhaust actually helps the fuel charge to burn cooler and slower. (Sounds like a contradiction, I know. But it's true.) It does this simply by diluting the mixture. The exhaust is, for our purposes, "inert".
Without the exhaust dilution, but with the lean fuel and advanced timing, the combustion temps go waaay up. Over time, it can (but not necessarily "will") burn pistons. It doesn't happen overnight, however.
The Trueleo pretty much comes with everything you'll need, except gaskets, and the occasional vacuum tube or hose.
It comes with a handful of hex bolts to bolt the the thing to your lower intake, and two allen-head bolts for the ends, where the clearance isn't so good.
I chose to replace all of the hex bolts with allen bolts. Makes it much easier to install (you'll need a ball-end allen wrench) and looks much neater.
When I first got my Trueleo (it was probably about the 2nd or 3rd one sold) the flange plate was slightly warped. I had to deck it with a belt sander. This was probably an early production issue, but it bears checking. (I've never heard anyone else complain, so it's probably a huge non-issue.) If you do this, be sure to clean it out thoroughly.
Good luck. If you have any specific questions, please feel free to ask.
If I don't see your post here, shoot me an email.
Edit - I just realized that you're buying a used one. Not a big deal. A lot of the plumbing and stuff has already been done for you.
This is what mine looked like, installed. Not exactly pretty, but quite functional.