If your listings are being fed to Trulia (by your MLS or broker) and you make a change to the photos and/or description at the feed source, those changes should be reflected on Trulia in 24-48 hours. The caveat is that any manual changes you make to your listings on Trulia will override the feed data. I like to recommend using the feed data wherever possible instead of manual edits because then you can be sure that the information is identical in all locations and if you do make changes in the future, they will automatically update on Trulia.
Account Manager | Trulia
You can add info to individual sites like Trulia-free account or pay more for more features. Good plae to answer real estate questions and get some buyers and sellers in return. Good luck