It might be possible to configure a terrain gen mod to spawn Forestry trees, but the mod itself does not make them spawn in the world (https://forestryforminecraft.info/trees:intro includes a theory for why they don't spawn in the world). You have to breed them, find saplings in treasure chests, or trade villagers for the saplings.
Yes they do. They randomly generate one here and there, not in biomes of their own. I've found them around. I think they're just the tier one trees though (like Larch). You'd have to breed the more rare ones.