Modding questions...

Soxxysox

I'm new and have a couple of questions about modding with Scripthook and that.

How would I Manipulate every type of ped in the world? this is what i've tried but can't figure it out.

foreach (Ped Zombie01 in world)
{

}

Also making a weapon spawn on the ground? I've tried this but not sure about the pickup type field?:

World.CreatePickup(weapon ,Pickup,Game.Player.Character.Position, WeaponHash.AdvancedRifle, 600);

I've been looking for tutorials can't find much stuff that shows about this and I'd also like to implement custom models/sounds?

Thanks for reading sorry if this is really basic but i can't find any tutorials maybe you could link me if there is some good ones?