Basic Engine Maint - Vdrive & Tranny fluid change

Hey guys,
I have an 05 supra with indmar engine and walters v-drive and zf hurth tranny.

Need to change the fluids and have a few questions:

V-Drive - manual says to only have a trained tech change vdrive oil - only says for this procedure not engine or tranny oil - wondering why? Okay to fill through dip stick hole?

Tranny - cant find the drain hole anywhere - know where the check fluid level is and can fill there but cant see/feel other ports.

Tranny - manual recommends to clean tranny oil strainer screen - where is this?

Rudder lube - what type of lube does this require and where/how do you apply.

Thanks for the help.
Cheers, Jeff