No doubt in my mind--Capella was a major colony. Still, most of the people got out and still need somewhere to settle. I'd say they'd probably go to some outlying systems. Other then that, much of the military and civilian hardware got out of there (yes, heavy losses, but remember the 3rd Fleet and 13th Battlegroup were basically engaging Shivans all around Capella--they might have only had a few corvettes able to help you, but then again they rarely sortie anything bigger then a Corvette.
Next, you're right---the Colossus wasn't an economical loss, it was a huge morale loss. If the morale causes the GTVA to mourn and not continue working, that'll become quite the economical loss. Also, the loss of the finest ship in the entire GTVA took thousands of officers, crewmembers, and pilots--most of them are some of the best in the GTVA.
You're right--but how much was spent on bringing them out of mothballs that quickly? If they were scrapped, their turrets would be removed, subsystems reused, and basically everything torn out. Just think of what happens when the US Military sells a military craft? They basically tear it apart, making it nearly useless.
Meson bombs--they wouldn't make a big difference on the GTVA's economy because they were research programs.
The fleets and battlegroups would be reorganized, probably bring a few mothballed ships back into service until shipyards lost could be reestablished and more ships could be manufactured.
The NTF had to be including the planets--after all, they need resources and a base population to fuel their military. It would be nearly impossible if only rogues joined the NTF--the NTF simply had too people. Also note that NeoTerra was an ideal--to setup a new Terran capital in the Polaris system (always visible from Sol). Remember that Admiral Bosch "Gave the Lost Generation something to die for"--much like the generations of the 14 Years War and the Great War. That being said, I think it's safe to assume that at least 5% of Terrans (not including those that are possibly still in Sol) would be willing to join the NTF as part of the military. Even with those numbers, the NTF was made up mostly of die-hard young men and women and older officers who still distrust the Vasudans (surrounding the core of Bosch and his highest officers). The fact that NeoTerra was an ideal, the core systems of Polaris, Regulus, and Sirius all choose to join the NTF by popular choice (before some of their fleets were absorbed into the NTF), and the fact that the NTF had such support to do what it did says that they're a wider-spread problem and rebuilding will not be easy. The core systems would likely be fine economically, but severely injured socially and politically (after Bosch dies and they're seen as rebels). They won't be like WWII Germany, Italy, or Japan... they're more like Cold War USSR (untouched but society is injured and politics is changing again).