VietnamVisaservice.com is a Non-Government/ Commercial website operated by VietHoliday Co., LTD. You can either apply for a visa though a Vietnamese Embassy in your country. The price of getting a visa at Vietnam Embassy depending on the country wich you are living.  You are advised to contact the embassy of Vietnam for procedure.

No, this type of visa is applicable to air travel only. Three international airports in Vietnam that you can get your stamp with this approval letter are: Noi Bai International Airport (Hanoi), Tan Son Nhat International Airport (Ho Chi Minh City) and Danang Airport.