Read-only on Text Field of the Tabular Form
Sample here is just to make one field (EName) read-only. Obviously more fields can be added if needed. To find out what number of wwv_flow.fxx is, please see Which Tabular Form Column is mapped to which Apex_Application.g_fxx array? by Patrick Wolf
The "silver" color is added to make it noticeable as read-only. More sample of attributes of document.wwv_flow.fxx can be found at Denes Kubieck's Demo under Code section.
2. Call this function from page's onload under the HTML Body Attribute.
Create a new page-level validation with PL/SQL and Function Returning Error Text.
Please see above link about g_fxx.
2. Create the HTML div tag with a defined ID in any HTML region. This will be the help text information. Note that initially it is hidden.