1. In the Dialog Odo was the one who said she would stand trial for her crimes.
2. They did return through the Wormhole in the book, as for the Prophets they did not stop them. How it was negotiated is unknown but the Prophets did not stop them.
3. As to why they didn't re-invade, the Federation has viruses that can infect their entire species and the Prophets are between them and the Alpha Quadrant first off. The Cardassians, Romulans, Klingons and Federation not taking any of their bull and in perfect agreement there would be no real way to worm their way back in. The Breen Weapon is now useless. (The book also says there was a weakness in their ships that when exploited caused them all to retreat so they abandoned the Dominion.) They have no foothold or bases that the Cardassian had given them before and no way the four Alpha Quadrant powers would let them get another foothold with another race, they would be gunning for the first Dominion convoy. Finally with the Klingon's, Romulans, Federation and Cardassians the Gamma Dominion is in a vulnerable state and maybe even at risk of invasion themselves. (The books also say there were uprisings in the Gamma Quadrant.)
So the Dominion is in no shape to re-invade and right now wants little or nothing to do with the Alpha Quadrant. (The books state they allow peaceful exploration.) As to if they will re-invade in the future, who knows but not for a while.