Jeff, when you are choosing your brisket, most of the time here anyway it is wrapped and on the bottom there's a styrofoam plate. How then can you get it to flex? I bet you have your own favorite butcher, Huh? Most times I'm at Costco or Albertsons.
In answer to your question, Yes, the packer cut refers to the flat and point together in one cryovac package. They can sometimes be difficult to locate. There is a local wholesale club called BJ's near me that carries packers, but here at least, the Sams Club and Wally-World stock flats only.
Yep, that's a Packer's brisket. Some come as trimmed and some are untrimmed. The untrimmed one may be cheaper pound wise but you are also paying for a lot of waste. The timmed Packer as had most of the waste fat trimmed away and you pay a little more for it.
I always use Excel Packer Briskets and have excellent results. If your feeding a small group, it's probably too much and you should go with a Flat or Point. When looking for a Full Packet Brisket, pick it up and bend it in half, end to end. It should do this with relative ease, if it doesn't, leave in the Meat case.