Or will it get attacked/damaged when I am gone?

Things like that don't happen when the PC is not in the area.

Are you talking about the player homes inside the city walls? If so, then nothing happens to them.

No. Your Hearthfire houses are safe while you're gone except... I did return to Windspeak Manor to find skeever in my cellar which my housecarl warned me of. I few swipes and they were gone and not a trace of them remained the next time I returned. A minor thing really but no huge monsters setting your houses on fire or anything like that. Will something happen along when you fast travel in or step outside the door? Don't be surprised but your house will stay pristine. Don't worry in that regard.