Woodcutter cuts trees in a larger area if you provide more torque/speed/power to it.
Enchanting it with infinity makes it replant saplings.
Indeed ! The not-so-subtle hint in RotaryCraft that you need (really, really, really should) build a vanilla spawner is the
Blast Furnace to make HSLA steel.
Once you have said vanilla spawner, you need (really, really, really should) to build a vanilla enchanting table and start using your levels to make books. Save those books for later for things like Infinity, Silk Touch, etc.,.
If you have other mods installed, it will be easier, but RotaryCraft works just fine without other mods.