Mileage is truly dependent upon the driver and how well kept the vehicle is so BestUsedTires is unable to give a mileage or time quote. BestUsedTires does provide the current amount of tread in 32nds of an inch on all of their listings.
The price provided on the listing is for the amount provided in the title. i.e. 4 Nice Michelin Pilot Hx MXM4, 225/50/17 So it would be a set of 4 tires at the going sale price provided on the listing, not per tire at the listed price.
All USED tires could be professionally repaired. Every USED tire is inspected at least twice, once prior to listing for sale and once again prior to shipping out to a buyer. Repairs could be performed during the first inspection as well as during the second inspection.