If it is the border between Vietnam and Guangxi, many Vietnamese can speak Chinese. If it is somewhere else, let's communicate in English. The English level of Vietnamese is generally higher than that of China. At least the Vietnamese I met in Vietnam have good English. If your English is not good, like me, I will use my poor English and sign language, so it will be no problem to walk from North Vietnam to South Vietnam.

As for the visa, I suggest you find a bigger travel agency and ask them to sign it for you, which saves a lot of formalities and trouble. Only 100-200 yuan is much more convenient than running the consulate by yourself.

In addition, I personally suggest that if you travel to Vietnam, don't take RMB with you and change it into US dollars, because it is difficult to exchange RMB there and there are not many places to exchange it.

I once swam across Vietnam with a backpack. . . .