Thanks for the additional suggestions!
Oil / Fuel stains: Roger, that'll be an easy fix to remedy. I'll plop some more stains up top where the fuel is already running down the side.
Ropes: Rather than redo the ropes, I'll likely just leave those as-is, and assume the guy tying down the gear had herculean strength.
Antennas: This always seems to be something I put off and sometimes never get around to. But that's another quick one I can knock out.
T48 Tracks: Roy, I hadn't looked into the exact track type until you mentioned it. Clearly from pictures, I can now see that the bulk of the track is rubber, with only the pins on the side being metal. I can make this more clear on the spare track armor. For the running track, I think they look alright, since they'd be covered in dirt and mud anyway.
Pistol port: This may be something I have to omit. I can see myself butchering the paint scheme trying to fix that up. If I think I can do a clean job of it, I may attempt it. Would some putty and skillful sanding do the trick, or does the current pistol port need to be cut down in depth? I checked the picture you linked Roy, and it doesn't seem to protrude as much as the pistol port on the model.
.50 cal Machine Gun: I thought about putting an M2 up there, but couldn't find any pictures of Fireflies with .50s. All the pictures and references I found showed them with .30cal MGs.