I know three beeps means it's purging an address that hasn't been in use for awhile. Mine quit purging and every now and then I have to do a hard reset to avoid slot max.
The throttle beeping is normal, at least mine was. I think there may be a way to mute it but can't remember.
Of course mine was a 400, not a 402.
Speaking of... anyone have a dt400 they'd like to part with???