Babychaosfloh_HD

I added a texture pack to my server and saw I only can force it. But I want to allow my admins to use things like X-ray. Some ppl said I could use a plugin in to handle my texture packs. How are this plugins called? How do they work? And for what version are they?

I watched the video about adding a world to a server, now I would like to know if the ppl need to be op to join the other worlds? Or do I need a plugin?