Thanks for Robert for detailed answer.
a) Which file needs to be edited for adding regex in input validation. Sorry I didnt go through entire JS files. I am fairly new to JS world and WAB.
b) I understand OR operator needs to be used. But in final widget screen I need to see single input text box, but when I un-check "Ask for values", screen looks like this. I want one input text box which should search multiple columns using OR condition.
c) I will try with IN condition
d) My question - when I include all fields, some of the columns contains value which is URL. This needs to be displayed as hyperlink in result window. I dont see any option to set a specific column as hyperlink.
e) My current application has options listed as a radio button , where user can see the choice and select and map /results changes accordingly.