First of all, I have to say a HUGE thank you for your help and answers. I actually expected people to tell me to just shut up and buy the books.
Shut up and buy the books!
(Hey, I didn't want you to be let down! Besides, I
wrote some of those books, and I need the money....)
Having said that, let me tackle your questions (some of which have been answered, but I like repeating things; I also like saying the same things over and over)....
I don't want to deal with spoiler tags, so I'm just going to go old-fashioned and do:
SPOILER SMILEYS!!!!!!!!!!!!!!!!!!!!!!!!

:thumbsup:
TNG
1. Yes, there was, and it was a major plot point in my novel
A Time for War, a Time for Peace (with some seeds planted in
A Time to Kill by David Mack, an earlier volume in that nine-book miniseries that chronicled the year leading up to
Nemesis that I highly recommend).
2. The Romulans were not overburdened with choices, and the alternative was to fight a war they were ill-equipped to fight. The specifics are in
Titan: Taking Wing by Michael A. Martin & Andy Mangels, with some followup in
Titan: The Red King by the same two authors and my own
Articles of the Federation.
DS9
1. Yes. See
Unity by S.D. Perry for Sisko's return and see
Bajor: Fragments and Omens by J. Noah Kym in
Worlds of DS9 Vol. 2 for more specifics.
2. In a manner of speaking, in
The Dominion: Olympus Descending by David R. George III in
Worlds of DS9 Vol. 3, but I suspect there's more to be told there...
3. Yes. The post-finale
DS9 novels picked up in March 2376, three months after the end of the seventh season. As of
Warpath, it's January 2377. Meanwhile, the four extant post-finale
VOY novels are in 2378, while the post-
Nemesis TNG books are currently in 2380. (Oh, and
Corps of Engineers is in late 2377,
Titan and
New Frontier are also in 2380, and
I.K.S. Gorkon/Klingon Empire are back in 2376. Cha cha cha.) And we've mostly been avoiding saying what the DS9 folks are doing in the later years. Mostly.
VOY
1. It's being studied, yes. What specifics there are were in
Homecoming by Christie Golden, but considering that technology's very existence in this timeline is a temporal violation....
2. No, she isn't. She was on
Voyager in Christie Golden's
Spirit Walk duology as a civilian advisor.
3. That Changeling was cast out of the Great Link and is on his own.
4. That was spelled out in
The Farther Shore by Christie Golden.
Hope that helps!