I work some in embedded systems, so here's some of my guesses:
Watchdogs = most likely # of times watchdog timer (in hardware) has fired. Usually a watchdog timer is used to restart the system automatically when the software hasn't "checked in" like it's supposed to on a regular basis (and that regular basis may be on the order of a few seconds). But I know mine hasn't rebooted ~5000 times since I've only had it about 2.5 months. So what this watchdog is doing, I don't know. My calculations average out my watchdog value to 70 times a day. I can believe the software missing some kind of time-sensitive mark that many times a day for at least something, though.
Boot Recoveries = possibly # of times a filesystem repair has been needed (and executed). I've got zero here and I've seen a 1 posted here so this sort of supports this explanation. As we know in some cases when a repair is executed it may not succeed, thus some people report losing their recordings.
AC Power Losses = Self explanatory. See self for details.
Queue Filled = Almost anything could be put into queues. Interesting, 255 is the value of a maxed out unsigned 8-bit counter, or -1 signed 8-bit.
Queue ID = Not sure but like the one above, 65536 is a maxed out unsigned 16-bit value, or -1 signed 16-bit. Being an ID, I'd say most likely it's -1 to signify "disabled" and goes along with the Queue Filled count for some future "feature".
DST = Not sure (couldn't be "daylight savings time", could it?). Showing in hex could likely mean an address or related value, or some bit-encoded "flags". My value has only one bit set, but is a quite different value from the 0x0003 (two bits set) posted here, which supports the bit-encoded flags.
Authorized Services = Not sure.
Suc(c)essful Downloads = Not sure what's being counted. I've got 19 but there haven't been that many releases in 2.5 months... Could be program guide downloads, but I figured that downloaded more frequently.
Previous Software = Self explanatory.
Lost Locks = (2 values) Possibly relates to the lock onto transponder signal.
Modulator Resets = Sounds like # of times some modulator(s), maybe the ones for TV1 RF out and TV2 RF out, have needed reset.
Last Connect = Mostly self explanatory, most likely the last time the receiver dialed into Dish to settle PPV purchases and other secret privacy invasions.
Again, these are guesses. Keep in mind, however, if any of these values seem a little low over your 522's lifetime to support a possible explanation, it could be that some of the values have only started being accounted with this software version.