17 year old Aussie here, needing advice when I get my chooks soon :) plus my story

Hey there, I'm a 17 year old from Australia :) my parents bought some chooks a few months ago, and I've been fascinated by them... I guess just the way they behave like us. I dunno, it's a bit weird :P

Originally we had 6 hens and 2 roosters. Bad idea. One of the roosters was extremely cranky, aggressive and bossing the hens around, and fighting with the other rooster. My dad went and killed it because it was so harmful, so then we were left with 7 chickens... and then one of our dogs killed one of the hens, so then down to 6.

Last week, they had been scratching around near an olliander (probly not spelt right) tree, which is currently shedding "pods", which are really poisonous. We didn't know it at the time, cause we just let them out during the day, and lock them away at night. Next morning = 4 hens dead. So we're left with the rooster and 1 hen :( my mum's friend felt bad for us, and being the avid chick-breeder she is, gave us three small hens, which had already been incubated and raised. At first, there were some territorial issues with the two big chooks, but now they seem to get along. They're still really small.

Anyway, because of my fascination with them, I've decided to get some of my own. They'll be locked in a different coop to my parent's chickens during the night, but I'm hoping to let them roam free during the day.

I've just purchased this off eBay:

http://www.ebay.com.au/itm/360435657898?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

What do you think? It would also look nice in my mum's garden :) I was thinking that it looked big enough for only two chooks (I plan on getting two hens for it), but maybe if once I got it, and it looked big enough for three, I could get a rooster as well. Would this be advisable, or would the two rooster's fight when they are close to each other? (just so you know, the primary reason was for eggs... though that's pretty obvious)

Also, do I have to leave the chickens locked in that house for a few days so they get used to it, and learn that it's their home? If I think of anymore questions, I'll ask :)

Thanks for reading :)