This is an update on getting from kunming to hekou and then across the border in the Vietnamese town of Lao cai to Hanoi. 

Overnight bus from kunming to hekou
My wife and I took the overnight bus from kunming to hekou last Friday night, a week before Chinese new year. It cost about 150¥/person. The bus wasn't that crowded and was clean. The beds (not recliners) are in three rows, are slim and not uncomfortable. They provide a pillow and blanket (not sure how clean these were). If you are tall and wide, you may be sleeping with bent knees.

The bus departed around 9p, stopped at 11p for bathroom break and again at 1a for an ID check by Chinese authorities. The bus arrived in Hekou around 2a and there was no bathroom near there that I could find. Most other travelers left at that point but we and a few others slept on the bus until around 6a.

As for being unsafe, i didnt have that impression. Everyone on the bus slept and there was a security camera. We and others stored our big backpacks in the under storage. We kept an eye on activity outside but when we arrived there was no sign of tampering. However, as with any mass transit, be sure to take precautions; I didn't leave valuables that weren't on or near me at any time. Don't give the thieves reason to give the bus a bad name. In my opinion the bus is a good, cheap option though you shouldn't expect a great night of sleep.

From Hekou to Laocai
When we left the bus, there were were several taxi drivers desperate for our business. We decided to take one because we didn't know the border was only 30min-1 hour walking distance away. Being near chunjie, the driver charged us double the normal price, 10¥/person.

We had gotten our Vietnam visa in kunming so at 7a we passed through the giant Chinese customs building (to the left of the bridge), across the symbolic dividing bridge, and into Vietnam. After going through customs on that side we were able to change some money at the counter in the same building (the rate there is about  30% less than a bank near the train station in Lao cai.). 

Getting to the train station in Lao cai
Outside of the customs building, we found several taxi drivers. We offered 20,000dong, a fair price, but they wanted 100,000! We laughed at their absurdity and started walking towards the street (the train station is to a kilometer from the border if you take the street to the right). Eventually one of the drivers  followed us and took our offer.

After arriving, we walked to the tucked away train station in a square. It was packed and there were no tickets available until the next morning. They only accept dong so we had to exchange more money at the Western Union bank on the corner. The soft seat day train cost us around 200,000d. We stayed the night in one of the many guest houses in the square. It cost 100,000d. It seemed that most of the hotels in that area are small and not well kept, probably because they cater to travelers staying only a night.

The day train from Lao cai to Hanoi
The soft seat on the train was actually a bunk in a cabin. We departed around 9a. There was one other family in the cabin when we arrived but by time the train departed there were 12 other people (men, women, babies) with us! However, this became one of our favorite memories as the other travelers were very friendly, exchanging food with us several times and never complaining about the cramped conditions. We were also able to see the picturesque countryside. This was a rich cultural experience for us. 

Arriving In Hanoi
When we arrived in Hanoi around 7p, we followed the massive, departing swarms to the station exit and were greeted by taxis. One of our cabin friends told us that during Tet 70,000d was reasonable to pay to get to the Old Quarter. We found a taxi and gladly arrived at our hotel.

We apologize for all of this information but we hope it helps you in your travels to Vietnam. We hope you enjoy the country as much as we do!