Hi Laurieh and WELCOME to the forum. May I suggest that you read though some of the many posts, especially under the topic of Gear Guide.
Personally I would recommend a Dome tent and I have a couple of DMH brand which I can thoroughly recommend. Size will be determined by personal choice. I have an 8/6, 4 and 3 person, a tent for every occasion.
Put a large tarp over it to give you coverage over the tent and the extra will provide you with kitchen-eating areas. In the tarp I recommend either Ultrarig or Durarig with the D rings.
A tarp over will also give you cooler in summer and warmer in winter.
Also suggest self inflating mattresses over just the standard air bed...much more comfortable. I'd go for 2 singes rather than one large, easier to handle that way and you can put them together as one.
I'd also recommend a low pressure gas stove, definitely safer and better performance as well.
Lights I suggest 12 volt fluros with a low current draw, something like a Versa Lite and you can run it from your vehicle.
Tables and chairs would be personal choice. For the porta potti I would go for something in the Thetford 165 size as it is not so low to the ground. You can get others that work just as well from places like Kmart but if you look at the Thetford you will get an idea of the size.
When it comes to a shower then I believe the 12 volt option in the bucket is about the best and again can be run from the motor vehicle.
Shower recesses are quite cheap these days and you can have either a single or double, again personal choice.
Fridge...is a big outlay and then you also have to power it so it is something you will have to do some research on. Might be a good idea to start off with a Tropical type icebox.
When it comes to this sort of item I suggest you talk to someone like Jamie at Dynamic Solar Solutions http://www.dynamicsolarsolutions.com.au/ Phone: 1300 076 527
and he is located at Moffat Beach on the north coast. Yes he is a bit of a drive but I believe Jamie to be one of the good guys in that he will give you all the advice you need without any of the pressure and well worth the drive.
Now if you want to go camper trailer..then that is a whole different ball game.