Pricey you've answered your own quesiton, it appears for all the right reason you should convert and replace the current heating system. Converting to gas is a lot cleaner and you won't have to worry about potential oil leakages underground or the cost of removing and installing it your basement. Removal can be very costly, including insurance for your oil furnace. Adding central air is a great idea, especially if the home has poor circulation. You might want to have installed along with the central air a whole house fan. The fan helps during the summer months in keeping the home cooler and not making your central air system work so hard. Replacing and installing these items will certainly help the selling of your home. It is hard to determine cost, because there are so many heating and air systems to select.
Valerie B. Chatman CRS, GRI
Prudential New Jersey Properties
908-874-3401 X 307