VISA HELP/ADVICE

Good day , we are two travelers flying into Vietnam, on the 18th of January, I am aware that there are now changes in rules to getting a Visa. we have bought a One way ticket to Vietnam as we are looking at working there, My question is, Will I be allowed entry on a tourist Visa and a One way flight, and can i once we have gotten a job there apply for a business visa without having to return back to South Africa