For that, we'd suggest you to please visit the nearest authorized service center of Kawasaki as they would be able to assist you with the exact maintenance cost and the schedule. Follow the link and select your city accordingly for service centers.
Kawasaki Vulcan S is available for sale and for the availability in your city, we would suggest you walk into the nearest dealership as they will be the better person to assist you because it depends on their stock book. You can click on the following link to see the details of the nearest dealership and selecting your city accordingly - Bike Showrooms
Both bikes have their own forte. If you are looking for comfortable feature loaded car with amazing performance and features, the Harley Davidson 750 seems like a better option as it provides a better punch and belt drivability makes the transmission of the power linear and low maintenance. However, the Vulcan S comes features loaded which makes it an amazing pick in terms of utility. Moreover, the bike also gets Monoshock suspension for the stiffer rides. If the Harly Davidson is compared, the Davidson manages to get twin shock absorbers at the rear for better performance. Moreover, we would suggest you to visit the nearest dealership to take a test ride of both the bikes so that you may evaluate the performance, design, and comfort of the bikes.