Well, depends what you're going for.

The initial enemy positions should start out stored near the map data, and copied to a dynamic buffer upon them being "activated" (i.e. you just entered the room they're in) and the stats for them you use should be in the new buffer.  It's your choice if you want to form a way so that the enemies can stay in the same state upon deactivation and reactivation on the same playing session, but for most cases that isn't what's done.

sure, I can provide a quick example -- what language, how many enemies per screen, size of enemies?

language is z80. Max is 4 enemies per screen. Their spawn locations can be random on that screen. Enemies are 1 tile by 1 tile (or 8 px by 8 px). Movement should be partially random, partially attack of user-controlled player.