If you move the Eglu and run around regularly, to give the grass a chance to grow back, it should be fine.
They can occasionally be noisy, it depends on their personalities. Some of ours liked to announce to the world, when they'd laid an egg!
Chickens are lovely creatures, plus you get the added bonus of fresh eggs. If you feed them good quality feed, their yolks will be a deep orange colour.
People often feed scraps from the kitchen, which they'll love, but it is actually illegal, so just a heads up there.
Beware, keeping chickens is addictive! We started with 3, after my DH finally relented, and at one point, ended up with 46 chickens in lots of different breeds, and 3 ducks, and DH was just as hooked as I was! We do have the land though!
The only reason we've allowed our flock to run down, is due to our ill health, but we really miss them. We now only have one old girl, (a Cream Legbar, she lays blue eggs) who is 10 years old, and still laying and going broody, bless her, and 2 ducks (a Cayuga, and an Indian Runner).