How exactly do the Tribunal and Dagoth Ur tap into the power of the heart?
I don't think there's any lore to clarify how you would go about tapping the heart. Just have some snappy mystic-sounding dialogue tree, and that should do the trick.
Here's the text you're looking for:
"The normal procedure for establishing connection with the Heart is a three-step process. The wearer of Wraithguard strikes the Heart with the hammer Sunder, causing the Heart to produce a pure tone. Then the wearer of the Wraithguard strikes the Heart with the blade Keening, shattering the pure tone into a prism of tone-shades. These tone-shades are then imprinted upon the substance of the wearer of Wraithguard, giving him an immortal and divine nature.
The Nerevarine will not be taught the secret rituals required to perform the third step. Instead, The Nerevarine will strike the Heart with Keening for a second time, causing its tones to diverge into unstable patterns of interference. Further repeated strikes with Keening will further disrupt the tones, with the ultimate result of shattering and dispelling Kagrenac's original enchantments binding the Heart, thereby severing the Heart's links with Dagoth Ur, and with any surviving Heartwights, and with the Tribunal. Destroying Kagrenac's enchantments on the Heart will also stop the corrupt effusion of the Heart's divine power, and end the Blight on Morrowind."http://www.imperial-library.info/mwbooks/dagoth_defeat.shtml
It gives you the first two steps there and tells you what the third step entails, it just doesn't give you the specifics. Following that should give you a solid outline, then just improvise for how exactly the tones are imprinted on the wearer of Wraithguard.
As for Dagoth Ur, I wrote http://www.imperial-library.info/cgi-bin/yabb2/YaBB.pl?num=1215227805 about that a while back which might be helpful...
Make up a backstory for some power that lets you be invisible to Dagoth. :shrug:
Chances are you'd have to be a god already to have that sort of power. Vivec talks of not being able to sense the Dwemer anywhere within time, Ur probably has similar sensory abilities - I imagine if you exist at all that he'll know about it.
Does anyone have a suggestion about Dagoth Ur? Something needs to happen to him no matter what, anyway. Should he be concealed in a prison of my creation?
Either that or make up a way to 'banish' him to the dreamsleeve, though to make that flow well you'd might have to do more research than you'd like.
There is a very simple explaination for leaving Ur alive: Once you have bound yourself to the Heart, he can do nothing.
You posess the tools and you can't be killed. Neither his Vampires nor the Tribunal can touch you. It's you're turn and you have everyone's king in check.
Not really. Both the Tribunal and Dagoth Ur have been killed in the past while being connected to the Heart, they just come back, you'd be no different. They'll still be powerful as well, all they have to do is mount an attack on you and take you out - sure you'll come back, but to say that he can do nothing is just false.
Why can't you just remove Dagoth's connection with the heart with the tools and then reverse the order to make yourself take his place?
To remove Dagoth's connection you have to shatter Kagrenac's enchantments on the Heart, shattering his enchantments results in the normal ending of Morrowind. Basically, you can't disconnect anybody else without ruining your own chances at harnessing the power...
On another note, I've never noticed the line
"The plan is to permanently disrupt Kagrenac's enchantments upon the Heart, severing connections with Dagoth Ur and ourselves, and rendering us all once again mortal. A mortal Kagrenac may then be destroyed by mundane means" in that text before... is that a typo? because seriously, what the hell...