I have a breeding pair of emus that I received from a friend about 5 years ago. My friend got into the "emu craze" when a good breeding pair cost thousands of dollars. Since he raised emus commercially he had hundreds of them at a time.
My pair are in a 100' x 30' run, constructed of 6' no climb horse fencing, with "t" posts spaced about 8' apart and wood braces about every 25'. My husband built the birds an 8' x 8' x 6' tall shelter that they pretty much ignore, even in rain, hail, heavy winds or snow. I do keep their feeder in the shelter to keep the pellets dry. When we discovered that my birds don't build their nest in the shelter we built a crude lean to over his nest... and that's where he nests every year!
My birds are fed a commercial emu pelleted chow made by Associated Feeds. Commercial breeders often use chick (emu)starter, then grower, then maintenance and/or breeder feed. Me, I just use an all purpose chow. I have a 50# metal feeder, along with a horse bucket waterer with an autofill float.
I have emu chicks that just hatched out on 2/28 that I'll be selling... probably for $60 a chick, which seems to be pretty standard where I live.
With emus, the male sits the nest for the entire 56 day incubation period. Enoch, my male, doesn't eat or drink during his nest time. He lives off the fat that emus have along their backs. I just had to separate my female from the male and his chicks as she will stomp them to death. I think she sees them as a threat... she's also stomped a skunk to death that got into their pen.
Emus raised by hand from chick size can be very friendly and easy to handle (as mine are). I took Enoch's chicks away from him and have them in a brooder to get them accustomed to being handled.
Emus are very curious animals. I have to be careful not to wear jewelry when I'm in their pen as they like brite and shiny things! One of Enoch's favorite "toys" is to tug on my jacket zipper pulls.
I couldn't tell you about using them as guard animals. I have llamas that serve that purpose. Hope this answered some of your questions... if not please feel free to PM me.