The Seven-Janeway-Doctor show didn't start until May 1999 ("Someone to Watch Over Me" [April 28th actually], "11:59", "Relativity", "Warhead"). She was on the show for 2 seasons when it was ensemble. Harry Kim & Chakotay had a fair number of episodes in Seasons 4-5. Neelix had 1 per season and was already obsolescing after Season 3 (Fair Trade, Rise).
The only person who had tension with Jeri Ryan was Mulgrew. Must've been some queen bee vs. rival young queen bee kind of fight. They were both quite professional to mask that hostility (which sounded like it was one way, from Mulgrew) given all the scenes they had together. Beltran couldn't mask his apathy. Wang could act his way out of a wet paper bag, but a wooden crate or barrel? Not quite.
As for ratings, I've seen 'em, have 'em on another computer. The premieres were a spike (Scorpion Part II, Way of the Warrior), but it's hard to separate out the new arrival from the event (Borg, Klingons attack). Ratings were high, but not as high over the next episode or two, and then returned to the normal pattern of declining ratings. Draw a steep line down a short distance, then change the angle to a long gradual decline- that's DS9 & Voyager's overall ratings over 7 seasons. Oh yeah, toss in a low spike for the finale, and a spike for DS9's tribble episode.
Seven seemed to work out better than Worf. She had a lot of good episodes and she had a good role and even came with her own 'playset' (Astrometrics). She was basically Sacagawea 2.0 to Neelix the 1.0, bringing Borg knowledge of races and space ahead. She was in the becoming human role filled by Data & the Doctor. She played the vulnerable/weak side of that quite well in Season 4 (the strength of being part of the collective vs. the weakness of the individual). Only over Season 5 did she turn into the typical superhuman like Data, Spock (the one immune to all the effects of something, with the occasional reversal where they are the only one vulnerable to something in one episode). They were able to get more out of her character than others, though Voyager writers were kind of lazy (Chakotay could've been interesting), though nowhere near as lazy as Stargate writers in late Atlantis into Universe.
Worf by contrast felt like he didn't bring much. Him doing double duty between DS9 & the TNG movies seemed very contrived. He would've been stronger as a recurring character like Martok, a special liaison to DS9 for the Klingon War then the Dominion War (basically like hired muscle, reassigned whenever DS9 needed him since he was the only Klingon in Starfleet and he brought tactical/weapon skills). He wasn't really necessary and only contributed to the Klingon episodes as an ally & confidante of his own kind to Martok. Dax's character turned from Jadzia into Kurzon when they decided to pair her up with Worf. She became more brash, boorish, losing all of the charm she had in the 1st 4 seasons. Worf episodes that weren't Klingon episodes were pretty weak ("Let He Who is Without Sin..."). He was good against the Jem'Hadar though ("To the Death", "By Inferno's Light").
