Since it's coming from Harvard, I'd say it's pretty legit. Basically they're using diamond anvil cells to achieve pressures on the order of megabars (millions of atmospheres), which is where the transition to liquid metallic hydrogen is expected to occur. They have not yet demonstrated the transition, but they are pushing the technology very close, and it looks promising.
An interesting thing about the diamond anvil cells is that since the diamonds are transparent, you can see what's happening to the sample under those conditions. I actually didn't know that was possible before reading about this. It's really cool.
That means if they do successfully produce liquid metallic hydrogen, they can subject it to a lot of tests and observe its properties.
Some good further reading here
As for the chances of Venus being more habitable if it had formed the same distance outside of Earth's orbit (i.e. at 1.28AU instead of 0.72AU), then almost certainly the odds of being habitable would be improved.
If Venus were at 1.28AU with the exact same atmosphere that it has now, then the ratio of new temperature to old temperature would be [math]
= 0.75. In other words, it would be 25% cooler. That's still much too hot to be habitable. But the evolution of Venus would have played out differently if it started there, and probably would not have the same greenhouse atmosphere that it does. We might even suppose that it would not have lost its water, and therefore maintain tectonics and a rock weathering cycle such that its climate would be more stable.