ADDENDUM:
I RECENTLY HAD SOMEONE PM FOR ASSISTANCE ON THE CONNECTION OF THE QUICK DISCONNECT/FLASHBACK AT THE PROPANE TANK, SO I'M POSTING MY RESPONSE - ALONG WITH PHOTOS - TO HELP CLARIFY. I WILL ALSO MAKE A NOTE IN THE ORIGINAL POST #1 INDICATING THIS INFORMATION IS DOWN HERE! ~De
Yes, you are right - a "flexible connection" from the hard pipe to the Flashback/Quick Disconnect is required. I live in So. Cal. and weather permits that I don't have terrible harsh conditions so I am able to use a piece of the T-Grade Hose to make this connection.
Since my set up is next to my garage, and because I bought a torch that has "barbed" ends for connection from the wall inlet of the propane, I cut one threaded end off the RED (propane designated) hose, and then cut an appropriate length piece of this cut end so that this hose section runs from the inlet nipple with the inside shut-off valve (attached with a hose clamp, nice and tight, and "bubble soap/water tested") to the torch.
NOTE: BEFORE CUTTING, BE SURE TO CHECK YOU HAVE THE CORRECT THREADED END (THE ONE THAT WILL ATTACH TO THE FLASHBACK) THAT WILL STAY STILL ATTACHED TO THE HOSE! 
Because I bought a 25' length of both hoses, I am able to use the remaining piece (my "run" from the propane inlet to the torch is about 8') cutting a length of hose that attaches to the outside portion of the pipe (also attaching with a hose clamp and similarly tested when complete) and using the STILL ATTACHED THREADED END to connect to the flashback.
Here's pictures of what I mean. Please remember to use appropriate GAS GRADE TAPE at all connections to insure a snug fit without leaks.
DON'T FORGET TO DO THE "SOAP AND WATER" TEST AFTER ASSEMBLY AND TIGHTEN AS NEEDED:
The Whole Propane Regulator/Flashback/Quick Disconnect set up as it will go together:
It's probably easiest to use this method for attaching everything together...
Step 1: Attach Regulator to BBQ Propane Tank.
(No picture shown)
Step 2: Attach Quick Disconnect to threaded end of Propane Regulator:
Step 3: Attach Flashback to Quick Disconnect (snaps in and out; colored collar slides in the direction of the Regulator to "release"):
Step 4: Connect THREADED END of hose to Flashback:
I purchased a brand-new, clean BBQ Propane Tank from Home Depot and have it filled at my local gas station that (luckily!) also carries Propane. If possible, that is what I recommend to insure you start with and continue to have clean propane at all times.
Hope this helps you out!
De