1. Cork on PVC pipe is what my good friend Steve Lucas over at the [url=https://www.exoticrainforest.com]Exotic Rainforest[/url] uses for his extensive bromeliad collection. I generally don't argue with his techniques, since he's doing all this in Arkansas and enjoys tremendous success. Check out some of his atrium photos - if you didn't know that his "logs" are made this way, you'd think they were real branches.
2. Once the bromeliads are established, it won't look like a PVC pipe wrapped in cork. However, if it bothers you, you can glue some of the orchid bark ontop of the cork. "Bark-looking" environment things are often plastic, and since what you're doing with the cork is providing a surface similar in texture and penetrative properties to actual bark, "bark-looking" isn't going to cut it - what will the roots hang on to there?
3. I'd move it onto the pipe. The sooner you start establishing your colony on there, the faster it will cease to look like a pipe covered in cork. Definitely rinse the soil off the base gently before replanting.
4. It has to do with the environmental adaptations of the different species. In North America, you don't have the wide range of habitats for broms to observe something like this; Florida and parts of the Gulf states are the only place that bromeliads grow naturally in the US. However, in the true tropics, and especially in Ecuador, there are about 20 distinct climate zones, all of which have bromeliads that are specially adapted to live there. The Bromeliaceae is a reasonably large family in the tropics, and there's a lot of diversity within it.
Vriesea are only found in fairly hot, humid forests, high up in the canopy of very tall trees, where they grow as epiphytes (hence my knowledge that they're bark dwellers and like to be humid). Below are Vriesea in the middle-amazon, 300 feet up in the canopy of a Kapok tree.
Tillandsia, on the other hand, are adapted to some of the harshest conditions the tropics have to offer - many species grow in deserts, and often at very high altitudes. These are often found on stone because that's the first place that water collects when the temperature of the day changes, or when there's fog or the area is inside cloud. Tillies are also found in our cold and permanently-clouded forests, where most other bromeliads would perish. Below is a blooming Tillandsia in the Imbabura highland desert, in Ecuador's north.
However, taking the cake for the toughest bromeliads are Puya, which are semi-carnivorous and grow in extreme altitudes and the driest of the deserts (the Atacama), where they are generally the largest plants. Below is a Puya cultivated in Quito, which, at 2,850 m above sea level (about 10,000 feet) is the lowest altitude where it will survive. I've seen these right up around the snowline (5,000 meters).