motarratha.lk is a Free service.
If you are putting an Ad for the first time you have to send a SMS with your name to confirm the phone number used in the Ad. (Please check your account area for more details.)
NO, it will only cost you normal mobile SMS charges.
Approving Ads is a manual process. Usually, ads are approved within 40 mins but it can be delayed up to 3 hours depending on the Ad load.