My dentist has advised me not to brush after a sugary meal or drink for at least an hour, otherwise you are effectively brushing the sugar into your teeth. Perhaps this also applies (but with a lesser timeframe) for meals that aren't so sugary.
Is there any possibility of another virtual currency - a Bitcoin competitor - being created? Surely this would have a big impact on the value of Bitcoin.
I'm not so sure. Google is stronger for software, whereas companies like Samsung, Sony, HTC etc. are better at hardware, which is my their marriage with Android has worked so well. The likes of Sense and Touchwiz do add some nice features, but they also add a lot of rubbish. It will take ages for hardware-focused companies like Samsung to catch up with Google's software experience.