I was bored, thats why I decided to do this:
(I'm new to the universe, so there may be errors in this summary. Please correct any if you are aware of them)
The Eight Divines Aedra make up the eight plane(t)s that revolve around Nirn (the planet setting of the Elder Scrolls series). They're all infinite in size, although some are bigger than others. That they show up as spheres is just an optical (and neurological) illusion. These beings were et'Ada (original divine spirits that participated in the creation of the world) that were especially powerful and gave up that power for the creation of Mundus (the infinite general area around Nirn), and provide the eight spoke-points of the border holding back the larger infinite area of Oblivion. They are mortal, like everything else that truly resides within Mundus, but that word has an unusual meaning -- while heard about a lot of et'Ada residing in Mundus that were turned to the Earthbones (transforming or dying into the framework that keeps reality 'real' and things with a stable form), "fading away" due to the interference from reality, and one case of being eaten and then pooped out by a Daedra and becoming a Daedric being, they're not something you can run up at and attack with a sword, most of the time. It's widely agreed that most of them have faded away or transformed themselves, and some sectors believe that they all have and the only thing left are reflections and rules left in the Earthbones, modified by other types of divine beings. They're Anuic in nature (by some definitions, as a criteria).
Yeah. You're basically right
The Ninth Divine, Talos, is a different type of divine spirit, just an Ada. Depending on how you interpret things, either one guy who was a hell of an Emperor and got ascended for being the best one, or three guys who acted very similar to an extremely powerful concept called the enantiomorph, he was normal people that "mantled", or walked the path of a god until the god began to walk they way they did (think goldwalking from Unknown Armies, but without the replacement thing). We've also seen the King of Worms ascend, albeit through a different method and a very unusual situation that might have limited his power, but the King of Worms does have his own celestial plane, a moon that sometimes eclipses Arkay's plane, so it's not unreasonable to assume Talos is somewhere in the cosmos, too. Like the Aedra, he's mortal, but it's not really something you can run at with a sword. Such ascended gods are timeless, so there's a bit of temporal oddness involved in this.
The temporal oddness is the Dragon Break, more specifically the Warp of the West, when Arctus the Underking got his Mantella/Heart back.
Like Talos, there are other ascended and un-ascended god-like beings. The Tribunal would be the best-known of these, and the most intentional of them. They were immortal, when Lorkhan's heart existed as a mantella;
I dont' know if you can use "mantella" regarding the Heart. But that could be me just being nitpicky about nomenclature.
even the complete disruption of their physical bodies would only be like a quick nap to them. Their power was related to the power they could channel through Lorkhan's heart, but their nature was divine, and as soon as they had activated the Heart, they had been deities present at the http://www.imperial-library.info/characters/trial_vivec.shtml. The power they had was borrowed without permission, but their own nature became divine with this stolen divinity.
The Daedra don't (usually; the four unstars may be special cases) have plane(t)s visible from Nirn, but they do have plane(t)s, as they reside outside of Mundus. That also makes them effectively immortal; typically they only create avatars on Nirn representing themselves that can only be dispelled, but even breaking on in its home simply sends the animus into the spare space outside the plane in Oblivion, which returns with its memory (and does so pretty quickly). They can be altered or masked through cyclical change or their own whims, but they are limited in ways that mortals are not; they can create lesser beings and things as part of themselves and their plane(t)s, but the range that they produce doesn't really match up to the variety found on Nirn, hence at least part of the interest in the world. They can probably still disappear if they wander too close or too far from their origin within creation. They're mostly Padomaic in nature.
The Serpent is made of unstars, as the recent Serpent thread would dictate. And Daedric Lords only have planes, not planets. Oblivion is perceived as space to mortals.
Then there are Magna-Ge, beings who helped plan or implement Mundus, but fled before it completed and completely broke them down. They don't have visible plane(t)s, but they did leave visible marks as they escaped -- the stars are the holes they ripped out from the fabric of Mundus as they escaped, through which magicka can flow in. The biggest of these holes was made by Magnus, the architect of the world, and is observed as the sun. For added fun, they're an infinite distance away, infinite-sized holes in an infinite-sized plane, and some seem different sizes. Chalk that up to mental stress.
Think you're basically right.
There's also the special category of Lorkhan. He's generally considered to be Padomaic in nature, but encouraged the Aedra to create Mundus, and his heart is the heart of the world. His body is dead and decaying, as it makes up the moons, but his nature is very tied to Nirn, which makes him a lot more effective than he might be otherwise.
There are also Anu and Padomay, personifying stasis and change, respectively. Other than the knowledge that they're outside of perceivable space, verifiable information about mortality and placement not available here.
Which is a real god? Maybe none, or maybe all, depending on your definition. It's more like a system of ancestor worship, Buddhism (see CHIM, if you can), or even nature worship than it is the typical monotheistic universe, though.
Right, though I'm not sure about the Buddhism bit, though I haven't read too much about Buddhism in a while. How do you interpret CHIM?