In general, this whole notion of the 'second officer' that seems very important in recent books is lost on me - yeah, Data was second in command, but it was just basically a 'coverage' thing - his JOB was to navigate the ship. Here we've got Tuvok as second officer and what? Tactical maybe, like he was on Voyager? I'm not even sure. We've got a security officer - shouldn't he be the one on Tactical? I've got the same problem with Picard's 'second officer', but we'll come back to her.
Navigating the ship was the job of Geordi, then Wesley, then a succession of minor guest characters and extras like Rager, Allenby, etc. Data's post was operations manager, the same job Harry Kim held on Voyager
. He also functioned as de facto
science officer, and was third in command after the captain and first officer -- which is what being a second officer means.
Tactical and security are two different jobs which are conflated onscreen for convenience. Security deals with internal crises and crew/away-team safety; tactical deals with external threats and space combat.
Initially, Ranul Keru handled both security and tactical duties aboard Titan
, per Starfleet convention. But after his injury, he had to be on reduced duty and Tuvok took over his tactical responsibilities. Keru is recovered now, but it's still a worthwhile division of labor.
I still hate Miranda. She's still barely able to remain faithful to her husband, who by the way is taking care of her less than 1 year old twins and 5 year old daughter.
She never actually stopped being faithful. The thing with Leybenzon never went beyond flirtation, and it lasted mere weeks before the events of Before Dishonor
scuttled it for good. And since they worked things out, everything's been fine between her and Vicenzo, as far as I can recall.