Here is a real quick list of what I ask. By no means an exhaustive one. But the most important is "Why are you selling?" That will get you to the motivation the quickest.
What is the property address?
What is your mailing address?
Beds/Baths/SqFt?
Is the house currently occupied and rented?
What do you think the property is worth?
Does it have a basement? If so, walkout? If not, crawl space or slab foundation?
Why are you considering selling when it is listed as "for rent?"
How quickly would you like to sell? (ASAP, 30/60/90 Days, Not in a rush)
How did you arrive at your sales price?
How would you truly describe the condition of the property?
Do you own it free and clear or do you have a mortgage?
If you have a mortgage, what is the amount owed and monthly payment?
How much cash do you want to walk away with at closing?
What, if any, repairs or update that need to be done of the following:
Foundation
Roof
Windows
Exterior Paint
Interior Paint
Siding
Electrical
Plumbing
HVAC
Doors
Kitchen updates
Bathroom updates
Appliances
Flooring
Water Heater