[Lampard]

toreduce high latency is to keep the gameserver "mods or plugins" as minimal posible.
latency realy depends on your specs and network speed.

No, mods or plugins do not use your internet, and don't make your ping higher, it may decrease your FPS but not your ping.

mods or plugins does use internet.
dynmap (minecraft plugin uses internet)

The plugins uses internet if its connected with some way, about mods, no they don't use ur internet, of course internet is used to download the mod from the server, but like when u are playing in a server and a mod is already downloaded, then it does not use your internet.