HOW DO I KNOW WHAT TO DISCLOSE?
The only way to know what to disclose is to use the Golden Rule. Would you want someone to disclose that information to you if you were buying a house? If so disclsoe it. If in honesty it wouldn't matter, then maybe not.
Of course there are certain items from the the Texas Property Code, Section 5.008 that are required by law. However, for items that are not necessarily on that list, you have to ask whether it would be important to you to know if you were buying.