The 18 is the closest thing to the 5.2 but every type of cats is different. I wouldn't look at that to much.

I would stick to the Australian guide for the 5.2 and just ask people on here about the things that you don't understand.

Mast rotation is very important and you can use it to flatten the sail or power it up. The diamond wires on the 5.2 are not as advance as those on some of the newer boats. No prebend on the 5.2. Mine are set so that about 5 inchs from the bottom attachment point it is hard to press them to the mast. I am not sure if that is the best setting but I know my boat keeps up with others well.

The mast rake on the 5.2 is not a big deal. I run mine with very little rake. Maybe 8-10 inchs off straigh up at the tip of the mast.

Downhaul on the 5.2 unless you have upgraded the system isn't something you can work. I set mine when I head out to the condition and adjust it if things change but I don't play the downhaul because I haven't upgraded to a system allowing that. Get the wrinkles out and then on big wind days crank down on it.

Outhaul, I have two rules for the outhaul, upwind all the way out on a sloop rigged boat. and then let it off downwind.

Alot of this comes from Rick Whites "Catamaran Racing for the 90's" There is also an 80's version that I am trying to find because it has a specific 5.2 tuning guide