I am a little surprised my expiration date still remains the same as it was prior to my upgrade... Is that correct -- upgrading does not renew your license term? It has been 35 years since my last upgrade so I am a little rusty in this area

That's correct, upgrading doesn't extend the license term. An upgrade counts as a "license modification", not a "renewal". It's the same situation as an address change.
Under current rules, you can't renew until you're within 90 days of your expiration date. It used to be common practice to check the "renew" box whenever you submitted the old form 610 for whatever reason. (I remember one time when I lost my wallet and license in the 70s, I submitted an out-of-cycle renewal just to get a new copy of my license.) Now you have to wait until you're close to expiration date to submit a renewal. The good part, though, is that online filing makes it much easier than it used to be.
Also, anyone know what percentage of extras do not have 1x2 or 2x1 calls?
I don't know of any definitive data, but here's an estimate. There are 43,680 1x2 and 2x1 calls available. VanityHQ says that 2694 of these are not currently issued, leaving 40,986 that ARE issued. N2EY's last posting in the "License Counts" thread says there are 129,918 Extras with current (non-expired) licenses. This means that almost 89,000 Extras, over 68%, do not have 1x2 or 2x1 calls.
(Note that this analysis ignores the few holders of 1x2s that are not Extras, the holdovers from the early years. And also note that almost all of the non-issued 1x2s and 2x1s are either date-controlled (meaning not available for reissue yet) or geographically-controlled (meaning not available in the lower 48 states).)
One other question -- what is the longest time you know of someone waiting for a particular callsign to become available?
Interesting question. I don't know.