No no no.
Braga never touched DS9 thankfully. So no, he was not there.
Jeri Taylor, not Jeri Ryan, was a co-creator of Voyager.
As to Manny, well, some people could see this as a good thing, some as a bad thing. All depends on your angle, what you think of his work.
I loved the Outer Limits which he worked on. I adored Odyssey 5, which he ran. And I think Enterprise has got better and he's been a force behind that. "The Council" was one of the best episodes yet, yet the season finale (written by Berman and Braga) just wasn't as good.
In terms of influence over the show... well, it all depends. Berman will still probably be around, but he's never been a major exerting force. He's more like a CEO. Braga will be the difference more than anything, it's always the name alongside Berman that guides the ship. I think Braga is, by all accounts, stepping aside. So he'll be a consulting producer probably, which means he'll look over scripts, but Manny will be left to guide the show. For better or for worse, we'll have someone new to give it a go.
Voyager is a classic example of the different executive producers pulling the show. Seasons 1 & 2, Piller. He went more on the danger, the isolation, the tension (the best years, IMHO). Season 3 (and a little bit of 4) was Jeri Taylor. She went the Janeway woman of power, more sensitive episodes. 4ish - 6 was when Braga took over (some of the worst years) which was largely about titty and explosions. Season seven was Ken Biller who did try to clear it up a bit, and season seven while not stellar did at least try to improve and tie up some loose ends.