Notice in the,first picture the small pieces of triangle balsa glued to the beams and firewall. Cut pieces of triangle balsa the full height and width of the firewall. Glue these with epoxy to the inside corners of the firewall and fuselage sides to make the firewall strong enough to support the gas engine and stronger nose wheel strut.
I just cut a hatch open like u see. The windshield is secured with screws to allow the hatch to be removed. Two screws at the front of the hatch hold it.
The ignition module is in front of the tank on foam rubber