Paris wasn't in "solitary confinement" in the modern sense. The cell has an open front and a fellow security officer sitting right there who would know Tom and talk to him. And it never said he was restricted from having visitors that I can recall. The "bread and water only" rations were ridiculous.
As mentioned,
Braga said the Borg baby was returned to its people offscreen. Perhaps unsatisfactory, but no further explanation required.
I figure that offscreen in
Deadlock before the intact Voyager #2 self-destructed, they used the cargo and regular transporters to beam over all the spare supplies, shuttlecraft, shuttlecraft construction materials, torpedoes, phaser coils, antimatter pods, repair parts, etc. to help the damaged Voyager recover by the next episode and get out of that ever-dwindling torpedo and shuttle supply problem. Oh, and they also sent over Harry Kim and newborn Naomi Wildman 2.0.
Also, the arrival of Seven of Nine, who integrated a lot of Borg advancements into the ship's system, would have eliminated a lot of the replicator rationing and energy supply problems.
Then the Hirogen takeover of the ship would have one positive side effect, which is the end of the holodeck energy supply issues, because they obviously put some of there powerful ancient energy sources to work to power the full ship-wide holographic emitters.
In their scans and wanderings of Arturis' faux USS Dauntless, the Voyager crew were able to get enough technical data to reconstruct the Quentum Slipstream Drive to partial success, so it makes sense they also might have gotten enough technical data to recreate his Particle Synthesis systems, which were in effect advanced replicators. That seemed like the basis for the future Voyager's replicated ablative armor hull plating, so in the near term I could see them using the prototype to replicate some new shuttlecraft, or at least the parts for them.
Harry Kim never got promoted because he was sadly already invaluable in the operations position he was at without being promoted, and Voyager was in a sort of promotional stasis (with a few exceptions) since they were stranded in the middle of nowhere. Regardless, despite his low rank he was a member of the command crew and led people on missions who outranked him on several occasions, so everyone knew what was up and that he was the head of the operations department, even if his rank did not reflect his position within the crew.
The Warp 10 Barrier in Threshold is no big deal because Starfleet always just recalibrates the warp scale. In TOS they would routinely travel into the warp teens, and then Excelsior's Transwarp Drive comes along and became the TNG-DS9-VOY warp scale, and the TOS Enterprise was recalibrated to cruise at Warp 7 instead. That got retroactively applied to ENT, DSC, and SNW as well with Enterprise reaching Warp 5 and Warp 7 by the end. In the future of
TNG - All Good Things..., the Enterprise was again traveling at Warp 13 or something like that, which will eventually get recalibrated based on Borg transwarp drive or Quantum Slipstream into higher and higher multiples of the Warp 10 Transwarp Barrier, so warp 9.99999999999999999 on the Threshold scale will get renamed Warp 7 or something cruising speed on the new recalibrated scale, for the sake of simplicity.
There's different definitions of transwarp. There's transwarp as in really high teens on the TOS-scale or multiples of Warp 9 on the TNG-scale (plus transwarp conduits and quantum slipstream). and then there's the infinite speed Warp 10 barrier of Threshold. Which really if you think about it is just an unlimited range version of the jump drive from
Battlestar Galactica... that admittedly turns you into a sexual dynamo salamander. But since the salamander thing is totally reversible and takes days to happen anyway, so you can be easily treated with a hypospray before it happens, why not use it?