New 2.4TD hilux surf owner

Hi everyone, I have just purchased a 1993 hilux surf of the 2.4 turbo diesel variety. After searching the web I found this site and sat up for hours reading all the articles (Very informative). After owning the vehicle for about a week now I am quite impressed after taking it for a drive of about 800klms and some minor off road work. I am a little disapointed with the fuel econonmy though getting to the E mark after only about 400klms is this normal?

I have a more few questions that I ask your help on answering

1. My hilux has a demister type push button switch in the centre console on the passenger side of the fog light switch. It has a blue triangle on it and looks sort of like an aggresive japanese man within the triangle. I can't find out what it does except for slightly raising the engine revs when at idle. I think that it would serve some other purpose as the vechicle already has an ilde up switch on the main console. Any thoughts much appriciated.

2. I would also like some information as to how the dual battery set up works. Is it one battery for accessories and one for startup or are both wired together for both purposes. My main reason for asking is for the possibility of hooking up accessories like a fridge, and making sure that i don't flatten both bateries not enabling me to start the vehicle again.

3. The final question is about insurance. I have rang at least 20 insurance companies about the truck and all except one has refused insurance. The problem is that the premium is $1710 on 60% no claim with $1600 excess.(quite expensive) I was wondering how everybody else insures there Surfs in Australia. Although both me and my wife are under 25 most of the companies refused insurance because of the vechicle, not because of our age. Please help me save a few dollars.

My email adress is listed for any advice.
Thanks to everybody in advance for your help.

Kevin from Sydney Australia.