Lua Scripting Questions

I have a few questions about Lua scipting. Please answer as many questions as possible:

1: How do you add NPC classes to garrysmod? (For example, how to make it so that yo can rescript an npc to look and act like the Combine Guard NPC)

2: What are the different holdtypes for weapons? (For example, how many ways can I make a specific weapon be held in the game when using it?)

I will post any further questions in periods of time.

Go to the LUA subforum please.