Burning the pine is how you end with a soil composed of 90% sand. Respecting the slow building of fertile soil is basic. There are several decicuous trees able to grow in very acid soils. Not so much in acid, plus sandy, plus salty.

A fact that is not being noticed is that pine trees forests evolve naturally to substitute the pines with a bigger mix of species so if you plant a pine monoculture you need to manage it to keep the monoculture. This forest evolution happens for free by natural means unless:

Sheep enter the forest or...

Weather is very cold or very hot or...

Soil is really poor, because wildfires.

Keep controlled this variables for a generation and the flammable monoculture problem will fix itself. All forests evolve to be eventually less flammable, but they need time to do this.

Possibly, but the other option is to let it return to barren wasteland. If left alone it'll find itself a new balance, eventually.