Composed with Deflemask. Just messing around with the Turbo Grafx. God I hate typing "grafx". The original track is the shit, if you've never played Gradius Gaiden, what the hell are you waiting for?
I don't think I've ever seen a TurboGrafx 16 sound remix, and the only PC98 ones I've seen are of Touhou tracks, so it's great that you did one. And yes, "TurboGrafx" is hell to type.
Irrelevant. You're talking about games which Konami devs had to fit into cards of 256 KB (2 Mb). That tune alone, which is a great cover, makes a massive use of samples and would eat up most of the available ROM.