Thank you all so much for the great replies and suggestions.. I have read them all carefully.
The chickens free range area is totally limitless. We live out in the county and there are few fences. Lots of interesting things for them to do... lawn, construction site with sand, gravel and rocks, a pond, the orchard, neighbours houses and their chickens, etc.
If a door is left open more than a few minutes (any door) the birds will walk right into the house, through the porch, down the hall and into the living room. They are poop machines. We will walk in and step in it with bare feet... which is not nice. We live in Thailand and its the culture to take off shoes before entering houses. The birds will be happily walking about the room. Thankfully we have all tiles in the house, so no carpet to get messed up.
I though about adding more birds (as I only have one rooster and one hen now). But then I saw the posters photo of a small flock on her porch.. so don't think numbers in the reason!
I used to have about 20 birds.. but we had a serious outbreak of fowl cholera in our province and most people lost all their birds. I was lucky that my rooster survived. He was the first to get sick and nearly died, but recovered fully.
He was on his own for a few months.. because it was pointless to restock as the disease was still about, and I was really upset about my birds deaths, because I had had many of them for nearly 10 years and they were pets.
During this time he got super friendly with our smallest dog and would follow her around everywhere. The both sat outside the front door together most of the day, and he would try to follow her into the house when I let her in for the night. He also got super tame with us... even though we did nothing to encourage it. In fact we got more of a welcome off him when we came home, than we did from the dogs. He would come running down the driveway to greet us, beating his wings, and escort us back to the house.
So, thinking about it more, this might be the reason they are like this.. because he thinks we are his flock. The new hen was really scared of us at first, but now she is as bold as the rooster (although she will not let us get near her to pick her up or hand feed her). The rooster is easy to pick up and 'throw' outside, and then she flies after him.
I am going to ask a friend to make us a small chicken tractor with a house attached. Then I can keep them in there and move them around the garden... and only let them out when I am in the garden to keep an eye on them.