Whats the use for it, and can i use castlevania 3: darculas curse or akumajo denetsu, or seprate?

oh ok so no akumajo densetsu with the kickass VRC6 chip. :(

Really if you want to run "any%" on the Famicom cart, just play Alucard! That's the fastest possible way to beat the Famicom version.

Cool

are the ntsc and ntsc-j split since they have only minor differences

The differences between those 2 are pretty major if you ask me. Alucard and Sypha runs are both easier for the JP version; Alucard's bat form consumes less hearts over time and Sypha's lightning attacks are stronger and more accurate.