Most of your answers are here M6620N Specs
and more are in this thread. If there's no hurry, read this entire thread and you'll find most all the good and bad of the device.
A few other answers: The relevance of PSIP or SCTE data is nada because it doesn't do "Season Ticket" type recording. Only manual programming. It's easy enough to schedule a recording and then expand it to weekly or daily or whatever. Wifi is dongle but included. It very low profile and has built-in antenna.
The time setting is a friggin P.I.T.A. and I could never get it right. I have to use Alaska Time with Daylight savings in order to get my clock right and matching the programming schedule. No internet or channel time settings ever worked - I'm in SoCal, BTW. Cable might work better as I'm strictly OTA.
I've never tried USB for updates as the internet connection works flawlessly. Audio is available via Coax, HDMI and Optical but I've only used the Optical.
Finally - I've never heard of a 5" sata drive so I'll assume it's a 2.5 incher
The drive "caddy" is a rather flimsy plastic snap in frame meant for a 3.5" drive. It should accept a 2.5 drive with a proper adapter (one that lines up the sata ports properly) but don't plan on swapping drives in and out. I doubt the frame will take much abuse, although I've heard no reports about breakage so that's good.
Couple of other things, SAMBA (windows file sharing) works well enough but NFS doesn't at all with jumbo frames enabled. Other things are scattered in this thread so scan it again.