1) I will consider using amx_hitmarkers as the universal cvar for this plugin. Seems fair enough to me.
2) Can u explain again what you're trying to do with read_flags() right there? I don't really get it
3) I don't really mind a HE grenade showing a hitmarker as it is also damage done to the victim
4) Won't be using that style, people consider using 255 0 0 to get the red color, the way you're doing it it will always choose a random number if one of the cvars is 0, which is not what we want.
5) I'll take you on your word about the HAM check and add it later on.