[Mandooz]

How to add moving NPCs in my server and let them talk with the players as if the player typed a command of /talk they open a chat with the NPC , (( Limited Chat )) OR even let the NPC walk in the city without talking .. How to create the NPC and do it ?

[GangstaSunny]

Use FCNPC do to this. It would be a way easier as using standard samp npcs.

[Freaksken]

To use prerecorded walking/driving paths, you can use standard NPCs.
If you want scripted paths (so that the npc can change where he goes when you want him to) you should indeed use FCNPC as GangstaSunny said.
To let NPCs respond to messages players type, use NPC:OnPlayerText, which is different from the player OnPlayerText version.