Singaporeans can stay in Vietnam for up to 30 days without a visa. Similar to Cambodia, international drivers licence is not valid and has to be converted to a Vietnam driving licence in advance. Applications have to be mailed in to Department of Transportation in Hanoi or Ho Chi Minh and there is a processing fee of VND 30,000 to 70,000 (under S$5).
Knowing which borders to cross in Vietnam is important. You don't want to make a detour that will land you in the middle of nowhere.
Cambodia x Vietnam Borders
International border checkpoint @ Ha Tien a charming & sleepy seaside town with some nice hotels, shops, markets, eateries, just don't expect everything to be open all the time.
Immigration Checkpoint @ Tan Chau is on the Mekong river and a passport office for immigrants. It looks like a jetty, do people really still come in by boat. Maybe the Vietnam citizenship services are still located here.
Cambodia Vietnam Border @ Binh Hiep is the main gateway. It looks like the suburbs with a grocery store, a petrol station. It's more for tour buses with large groups of people.
Border checkpoint @ Moc Bai that is a built up area with backpacker hostels, eateries and even a duty free at the border. Do stop by the duty free if it is open as I hear the liquor is cheap. Dirt road is big enough for a car or motorbike, I don't think tour buses can come through here.
Laos x Vietnam Borders
There are numerous borders each identified by a number. However, you really only need to know 2, one on the southern part of Laos and one on the northern part of Laos.
Laos Vietnam Border 605 @ Lao Bao is the main gateway and leads on to a sprawling border town. Located on the southern part of Laos. Checkout the picture of the gateway above.
Border Crossing 113 @ Tay Trang a picturesque hillside highway. Located on the northern part of Laos.
China x Vietnam Borders
There are many smaller borders not mentioned here. These are just the main ones of interest to me.
Located on the western part of Vietnam there is hekouzhen @ Lao Cai. Lao Cai is a big border town with public buses, community market and tourist spots for sightseeing.
Located on the eastern part of Vietnam is dongxingzhen @ Mong Cai. Another big border town with 4* hotels and service apartments in addition to regular homestays and backpacker inns.
Also located on the eastern part of Vietnam, next to Hanoi is Vietnam citizenship services @ Dong Dang.