Believe me, once you use a DVR you will wonder how you lived without it. How many times have you wanted to watch 2 or more shows that were on at the same time, were on when you had to go away or after you went to bed, or had to step away from the TV for something? You can start watching a program that you have recorded, stop it and resume at the same spot later on. The DVR keeps a rolling buffer of up to 1 hour or till the last time you changed a channel. I don't know how many times either my wife or myself is yelling out "Pause it"
There is no fee for an EHD on a 722 and you can use as many drives as you want, but only 1 at a time. They just eliminated the fee on the 722 in Feb. The $0 for the 211 is a 1 time fee only. I just added the HD to my 211 and I wonder why I waited so long.
In order to get the 2 tuner receiver, you have to get a dvr. Yes, the installer will run coax from the DVR to the site of you SD TV. All the tuners in the DVR will record HD. The TV2 output via coax will be down converted to SD. If you are using an OTA antenna, only the TV1 output will have your locals in HD from the antenna and all the sub-carriers (ie. PBS Create, etc) TV2 output will have your locals as supplied by Dish.