As far as the Dominion "Rebuilding their forces", as it were...
In one of the missions, you're sent to search a planet due to reports of a New Link being formed. Eventually you do find the New Link, where a Founder comes out to tell you that they just want to be left alone and aren't at all interested in fighting with the Federation again. One particular changling has been causing the trouble, so they hand that one over in exchange for being left alone.
I find it pretty odd that the Cardassians and the Dominion are so pacified in STO, while people who the federation was on fairly good terms with have gone completely off the rocker. Not totally unbelievable though.
There is nothing odd about the war between the feds, klinks, and roms. All 3 were not too friendly with each other during all of TOS, and most of the TMP-era, the feds and klinks were also at war before the dominion war got into full swing. And the destruction of Romulus has fueled the roms hate for the feds.
I find it more odd the dominion and cardy's work together at all anymore. Near the end of the war, the cardys double crossed the dominion and joined the fed\klink\rom fleet in liberating cardassia. In response the Founders order the cardassians "exterminated," and not just military targets, but ALL cardassians.
Humans have a food dependency but humans who are assimilated don't eat.
I think that the Borg wouldn't need to "cure" the dependency so much as just provide their bodies with the right nutrients.
DS9 has shown that Ketracel White addiction has been impossible to remove even through genetic manipulation, so the only reasoning I can think of Jem'Hadar Borg don't just drop dead after a couple of weeks is that the borg assimilated someone who knows how to make it, and they keep the nanites producing it since obviously, Jem'Hadar drones are all kinds of bad ****in ass.