1. You can use global_npc.pl in your global folder to do global NPC drops on NPCs above level 51 like this:
Code:
sub EVENT_SPAWN {
if ($mlevel > 51) {
if (quest::ChooseRandom(1..100) == 1) {
$npc->AddItem(ID);
}
}
}
2. #npcspawn create creates a new NPC which explains why it copies some data. It also adds a spawn entry based on that new NPC. Try using #npcspawn add and modifying the spawn time that way.