Alright. It's not that bad -- mm, no. It'll be rather tedious. I have a solution for your first problem. If there's any hope of getting this bird to fly we might as well start with the reactor and the fuel cell. Now I have a lot less experience with a Banshee than I have with a Valkyrie. Had it been the latter I probably would've handled most steps by myself in a somewhat reasonable timeframe. I'm not in the mood for browsing the DarkNet for a user manual on how to repair a Military-grade Heavy Fighter like yours so we'll do it the other way around.
Shortly before offering you the opportunity to make something out yourself I paid a visit to a few old contacts. For a modest amount of credits they provided a few crates of spare parts for my Valkyrie. Scavenged stuff and nothing more, but good to make use of in a pinch. You can find them in The Wayfarer's hangar. That's my home and place of respite for my Valkyrie.
You should be able to find something compatible with your ship. On top of that I can sell you a reactor that fits. It's a slightly downsized version of what they used on Valkyries, mind you. It served me well while I had it and still works just fine at about 71,95% integrity. This one was refurbished by ALG as a custom job. For any other ship I could've just slapped something else on. But yours isn't 'just any other ship'. Sometimes you just can't replace original parts. This will run you a few credits, plus the servicing fees where applicable.
You can probably fetch an OMG-series array on your own from the Omegas. They're easy to come by for the most part. Just take a look before buying. Some tend to be sold with pre-installed external rust or heavily corroded exhausts.
Let's start small for now. Custom mods can be added later down the line once every single defect has been compensated for. Or at least noted down somewhere. You don't want to play the guessing game of what broke on your ship only after you installed all the fancy upgrades you thought of.
One last thing. I hope you considered paying Nenet her fee. I need 200.000 Credits from you within three days. Unless you decided to skip a few steps and paid her yourself that massive fee of 350.000 Credits.
"Test the sharpness of your sword against another. And when that is not enough, unsheathe your cunning as the hidden dagger that ends the fight."