The VS Castlevania Reproduction Daughter Card is a Nintendo daughter card reproduction. It is compatible with the PPU list in the drop down list now, so you may use whatever PPU that you already have!
This daughter card does not come with a PPU or CPU.
Can this card be used for top gun also?
You would need to change out the ROM and supply your own CPU and PPU. This is an exact duplicate reproduction of the original. Unfortunately, I only supply Castlevania ROMs with the kit, but, you as the end user can replace the ROM and be able to play Top Gun.
Are PPU 0001 to 0004 referring RP2C04-0001 to RP2C04-0004? I bought VS Super Mario Bro ROM kit with PPU but I haven't got it yet. I think the PPU is RP2C04-0004.
Correct. Just the last 4 digits signifies your PPU with this kit