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.)
3) Are there any hidden fees/charges when sending SMS?
NO, It will only cost you normal mobile SMS charges.
4) I sent confirmation sms with my name. Why is my Ad still pending?
Approving Ads is a manual process. Usually ads are approved within 30mins but it can be delayed up to 2 hours depending on the Ad load.