Well, I've just speed-read this thread and you're doing an excellent, and much-to-be-admired job!
I started building something similar for my five year-old and it just grew into something bigger.
Only trouble is, he's 9 now and there still aren't any trains running, let alone scenery...
There's an impressive 4 track scratch-built viaduct, goods shed and station building though...
Keep up the excellent work. You're really putting me to shame