I have read only a couple of pages, so I apologize if my points have been already brought up.
I very much like the idea of high level combat being more defensive. Fresh captains are much more prone to fatal mistakes, while veterans may be long waiting for an opening on either side.
What I don't like is the idea of weapon range bonus based on fleet size.
1. Not sure if bigger fleet isn't already enough of an advantage on its own
2. I'd imagine that pooling sensor data wouldn't be some arcane, specialist technique. The ships already have sensors, communications and computers, so the only prerequisite is the software and maybe a crew member operating it. A relatively tiny dedicated piece of computing hardware at most, an overclocked i7 would probably do well.
3. It suggests that all weapons, regardless of technology, have their effective range limited by targeting. During combat we experience the fact that they simply deal no damage beyond their range. Is the additional info enabling more capacitors in my lasers and pouring more fuel into my missiles?
Speed and maneuvering bonuses make sense, as better information gives better foresight and the mechanic can represent small decisions that are not being simulated. Damage bonus makes sense too, more data about the target can help.
You can explain arbitrary balancing mechanics by technology, but at some point all reasoning becomes an equivalent of "a wizard did it".
When it comes to fleet combat being a compelling, viable option, the single biggest deterrent for me is the lack of control. I would love to be able to assign roles or simple scripts to my ships. Define preferred range based on shields, armor and hull, how far from allied ships should they stray in pursuit or retreat... Switching those behaviors during battle should cost command points.
Mechanic like this could also help the AI understand some custom loadouts better. "This one is an emergency defense weapon, please don't be suicidal with it".
For sensors I'd love something more involved than a "better sensors" hullmod. Not necessarily active systems like Apogee's probes, but some numbers to crunch. Building a dedicated sensor vessel with reduced profile relative to its scanning range, maybe have some per-weapon damage bonus so that pinpoint weapons would get more out of better sensors than big boom destructors.