Good start so far. Drilling the .50's is worth it. I do it on most of mine. Take your time with this build, dont rush. And if you dont know what dry fitting is you better become familiar with it, soon. There are problem areas on this kit that you'll find, I promise.
FYI, the interior on these should not be overall interior green. And fire fire extinguishers were not red in WWII either. The four openings in the wings behind each engine, these are vents, not exhaust ports, so dont paint black coming out of them.
Any questions, just ask.