For the sign, did you assign it's event number as #0500? And did you also make sure the flag bit 0x2000 was set for the sign's entity? It's "PC pressed down to run script", which means when the player walks infront of it and pressed down, the event assigned to it runs.
As for the second problem, do you mean how do you set their appearance? That involves setting the right NPC.PBM to the right slot in the Map Properties. Midorin, if I remember correctly, is the fat mimiga? He uses the Guest sheet, probably in slot one.
Also, you're not modding over another mod, are you? That'd be frowned upon {Unless the original maker gave you permission}, unless you're just trying to learn from it.