The sale deed is to be prepared and registered by paying the registration fee and the stamp.duty in the sub registrar's office and it shall be registered in office in presence.of all the parties witness and sub registrar.
There is record of every land in sub registrar's office, the title document from seller as well as search report from sub registrar's office for that survey number the land is situated..(7/12 record)
Yes once you own the title of land vide sale.deed you.can sale the property to single or multiple buyers with a registration at subregistrars office by paying the requisite stam duty and registration fees.
Also for purpose of checking land records and title the website landrecords.karnataka.gov.in can be used but for purpose of sale the certified.copies can be only used