Do any of you know if we have to manually activate the event in the server settings or if it'll be automatic?

Also, do you know if we'll have to manually adjust the rates to match the rate boost of the official event or if that too will be automatic?

Per WildCard you'll need to set the flag for Easter, should be in the Advanced tab.

You will retain Chibis, Skins, and Emotes from Easter event when it get patched out later.

All rates will be adjusted while Easter is active.