The visa thing can be an issue, if you're going to work for someone here make sure they will help you with this. However, so that you know what you need make sure you research the visa issue on your own. A 90 day visa is not a problem and I saw six month visas being offered through the Vietnamese Embassy in Cambodia, but nothing about one year visas or temporary residence cards. Of course you are probably aware that you need some sort of visa in advance just to gain entry into Vietnam.