Jeff, congrats on your purchase..... as you can tell, many have traveled your path, and recall the early days

And there humor is warranted, and quite funny also....
There is many slippery slopes in the world of ww tools, Festool is surely one of them.....
The good news is IMO, you started out with Festools "claim to fame".... their saw/rail system affords you the ability to do work that can equal that of a good sliding saw, or panel saw, costing $5k - 15k price range, (which you can't fold up and put in the corner of a garage) so in that regard, considering your purchase a "large savings" vs. a "large outlay". It will make you feel better. In addition, the dust system is superb for a saw.... yes, it makes sense you will want the MFT3, some more rails to round out your cutting system, maybe the parallel guides...
From there, the slippery slope can continue, however, I can honestly say, that many of the other tools Festool makes, do not have such a massive advantage over competitors products, so if limited by budget, you can stretch your future tool dollars further. However, if you are diligent about dust extraction, you may find yourself continuing with Festool tools.... specially routers AND sanders, again, two lines that Festool excels at vs. the competition.
Yeah, I drank the kool-aide too, but for me, its mostly about dust collection, high quality tools, and the desire to support a company who is first class with customer service. It's rare we feel like that about a company in todays big box store society. Try talking to a DeWalt tech rep, or Bosch...
Oh, back on subject...the one mistake most people make with rails is... be sure to get a rails long enough that hang over each side of the sheet goods you plan to work on to support the saw at the begining of the cut, and the end....very important. For me, I have learned for best possible straight edge cut (glue ready) plunge the saw; down into air, then push saw through the wood the entire run, turn off saw, let blade stop, plunge up.