Convert Text String (Date Info) into Date Values

Convert Text String (Date Info) into Date Values

We have a number of reports where the data is coming from web input and is slated to be scheduled "daily"
As such changing the Datatype of the field from Plain Text to Date would cause the scheduled "fetch" to remove the Date Values.

Questions
1) Why can't Zoho Parse a text string (7/26/2011) into a Date DataType during the import - reason for the question is that we will probably learn that we can create a custom formula column but over the course of a 100 reports we have over 500 date fields to "formulate"
2) How can we create a Custom Formula to convert 7/26/2011 to a DateType

TIA for your time