Why don't Aedra dabble in the affairs of men? Is it simply part of the pact they made, is it principle, or is it some other reason? Where do they exist, and can they even reach Mundus?

they are mundus..if I remember correctly... They're not as strong as daedra because they became weaker when they created mundus.... but they do help humans.. but less direct then the Daedra lords.... espacially by helping or sending certain "great people" like the Nerevarine and The Champion of Cyrodiil... also they often have some kind of avatar walking around Tamriel.... In Morrowind there are quite some.. I can't remember one so fast for Oblivion (besides Akatosh's avatar)... some say the prophet but I don't know really... although he gives Talos' blessing to the CoC... hmm..... he'll probably be an avatar of Talos..

The Eight Divines are the planets around the Mundus, The Magna-Ge fled to Aetherius, and there remain.

The Divines died/weakened themselves when they agreed to Lorkhan's "divine contract of creation." Mortal myth has reattuned them, to an extent.

The current state of the Aedra is abit, odd. Of those that didn't die or degenerate into the Aldmer, most either left with Magnus or departed following the Convention:

"After these two acts, which is commonly called the Convention, the gods left the earth."http://www.imperial-library.info/obscure_text/nu-hatta_nu-mantia.shtml#5

The Convention refers to the period just after creation spanning the arrival of the Adamantine Tower, through the war with Lorkhan, and the creation of Red Mountain. This is the first half of the Aedra's story, of them creating Mundus and dying/procreating/becoming earthbones/departing to Aetherius.

The second part is here:

"The people of et'Ada believed for so long and so well, that their beliefs may, just may, have drawn upon the energies surrounding Tamriel to bring the gods themselves into being. If that is so, the conflict between the Light and the Dark provided the energy, and the et'Adans the structure, that created the gods of Tamriel."http://www.imperial-library.info/dfbooks/b055_lightdark.shtml

The gods create man, and man recreates the gods.

So, the Aedric interaction with Nirn is a result of its interaction with them, they get legitimacy and power through worship and belief. However you can't say that the Aedra don't dabble in the affairs of men unless you just haven't been paying attention. What do you call the end of Oblivion? or the avatars of various Divines in Morrowind? or the blessings of the alters and wayshrines? Or the wind, the rain, the fact that time works in a linear fashion? All these are the Aedra being involved. They exist both as part of Mundus, in Aetherius, and as part of myth which due to the nature of the universe is just as real as the ground you walk on (which coincidentally could be seen as them as well).

I didn't mean that so literally, Luagar. I'm just saying, you don't see Aedra shrines all around Tamriel, and then suddenly one talks to you to get you to do all his or her personal bidding.

What? Yes you do.

And I think you're taking Oblivion's version of Daedric statues in the wrong sense. In reality, the Daedra are only supposed to be summonable on certain dates. And the tasks range from menial (Sheogorath had you find a fork and kill a giant Netch with it) to caring (Malacath had you save his Ogre children...which I think is horrible, as it's making the assumption that Ogres and Orcs are related somehow...) to devious (Sanguine had you make everyone get naked at a diner party) to profane (In Morrowind, it's debatable that you were just Azura's lap-dog).

On that note as well, Daedra only every interact with mortals because of two reasons:

1.) They could be called 'jealous' of the Aedra, because humans seem to like them more for their contributions to Mundus; Talos The Mantling aside.

2.) They're simply bored.

What I was pointing out was that on the one hand the Aedra do interact with mortals but its just not through the same mediums or as upfront as the Daedra do, and on the other that what we currently view as the Aedra is partially their mythic recreations so they're possibly limited by not having any actual corporeal form to speak of - also, though I haven't thought it through, I might go so far as to hazard that they're limited to interacting with you to when you interact with them due to that mythic nature.