Let me start.
Storyline and periodSince the topic is partially about a TC, then the speculations as to the state of Morrowind should center around a certain date. The most interesting time, of course, is the time of the Battle at the Red Mountain - around 1E 700. The records state that the The War of the First Council lasted from 668 to 700 1E, however a lot of historical events are exaggerated and biased. Thus, it is possible that, the PC could arrive before the war has started, visit Resdayn in all its glory, play a role in war and at in the descisive battle at its end in the space of a few years.
General Land overview:Resdayn is a country of two united peoples – Chimer and Dwemer. Both are ruled by their own kind and were united 300 years prior to drive Nords out of Vvanderfel. It is a time of “unprescedented prosperity and flowering for both cultures”.
With a notable exception of Bitter Coast, the lands are much greener and more fertile. The Red Mountain has not erupted.
Dwemer culture vis-a-vis its state in Morrowind is restored. Dwemer freely walk the lands to trade and interact with Chimer. Many achievements such as Observatories and Flying ships work and could be observed. Entrance to most colonies is free. Dwemer specialize in science, engineering and alchemy and trade their products freely with Chimer.
Chimer are dominated by Velothian culture. Wisard towers, Dunmer strongholds, ancient cities, now forgotten, span the countryside. Chimer are more proficient with the land and magic. They actively worship good Daedra in their temples.
Ocrs and Nords are relatively common in Resdayn, but not welcome. Nord occupation is still remembered and most are simply in search of adventure, not staying to settle. Orcs are seen as alien and primitive and are liked even less. Altmer and Bosmer visitors are rare, but more welcome. All other races known to ES IV are either unheard of or nonexistant.
Both peoples of Resdayn have “more habitable” and “less settled” areas. Contrary to original Morrowind, this division of lands should be much more striking. In some lands people are working peacefully, others are full of suriving Nord raiders and outlaws. Same can be said about wildlife, there are areas where it is roaming, others where it has been “pacified”.