That Kermit's guardian is almost as old as he is! :P

Nowhere close. Check my profile.

Maybe time still passes 1:1 with our real time but the Earth spins faster.

If Destiny's day/night cycles are actually 24 hours, then wouldn't we appear to be moving in slow motion to normal people if it only seems like an hour and a half day to our guardians?

Are we assuming the arrival of the Traveler had no effect on Earth's rotation? This math is using a 1:24 hour ratio as a day. Maybe time still passes 1:1 with our real time but the Earth spins faster.

Otherwise...

Since our ghosts can revive us I guess they can keep us from aging too?

Apparently so. Lord Saladin and Lady Efrideet have been around for over 500 years post initial revive.

Are guardians ageless but civilians still age like normal?

Presumably. One of the most recent Grimoire cards has Cayde-6 roping Shaxx into mentoring some snotty City brats, trying to teach them to win at dodgeball.

What determines who can be guardians? Can ghosts only revive guardians?

We don't have a fully account by any means, but it seems like Ghosts search far and wide looking for their Guardian. They sometimes even travel beyond Earth before finding theirs. So far, it seems to be a 1:1 ratio... Except for possibly Shin Malphur who may have inherited Jaren Ward's Ghost... somehow... without ever dying...

If ghosts can revive and anti-age, is humanity really in threat of this cabal attack?

Absolutely. In game, we can always reload. In the real world tales within the Grimoire, killing a Guardian then targeting his or her Ghost as it moves in to revive them is a strategy we've seen used by Lord Felwinter and some of the pre-City warlords. The Cabal were also very interested in finding a way to prevent Guardians from reviving.

Do ghosts only survive if the traveler is "alive"?

Unknown.

If the traveler/ghosts die, do the guardians suddenly age rapidly?

No. We have Eris Morn as an example of a Ghostless Guardian.

Do Awoken have longer life spans than humans?

Yes. Very much so. There's a couple of references to their long lives that you can track down. Mostly in item descriptions I think. And Exos have been around since the collapse... though most seem to have had their memories reset a few times (as in Cayde-6).

Can we be revived if we are blown to bits?

Almost certainly. I can't recall any specific references to Guardian dismemberment, but we routinely get hit by rockets and evaporated by Supers. So far, Guardians seem all but impervious to attacks that stop once they are killed. Only ongoing attacks, like the Awoken bombing a Fallen position that Guardians were currently attacking, has been shown to kill Guardians (and their Ghosts) with standard weaponry.

Of course the problem looking at it that way, is that while we play our guardians then never sleep or poop. If only we had Guardian Apartments…

I always assumed our guardians live out of their spaceship, which is why they don't have apartments. When we go to orbit they're getting downtime. The ship is like a space RV.

Speaking of, I'm requesting this ship in D2.

I'm not saying it's transmat...

But it's transmat.

Destiny is actually a temporal non-linear recompression of variant timelines rechecking to reach a perfect timeline where "The Guardian" achieves everything that is required, up to and including existing simultaneously with themselves to accomplish greater tasks.

At least that is he only way any of it makes sense.

Does the earth rotate in 1 hr when viewed from the moon?

You know, that always bothered me about our concept of "day". The Earth isn't standing still while it rotates around itself, it also rotates around the Sun. So is a day a complete revolution around Earth's axis, slightly less or slightly more? Also, Earth's orbit isn't a perfect circle, it's rather elliptical, so different positions of such orbit would mean different orbit speeds which would again change how long it takes for the Sun to appear in the same place in the sky it did yesterday EVERY SINGLE DAY. So, what the heck?!