Are timber look tiles any good?

Some are, some are not, this is one area where you get what you pay for. Make sure you get samples, big enough sections to really be able to see the final.  You can still find some decent looking cheap stuff, but unless installation and the sub floor are perfect is perfect, you could have other issues.

If they are from a quality tile manufacturer then they will be good. They make a very durable and attractive floor if properly installed. 

No idea but they use bamboo for scaffolding in the far east. Bamboo is a strong and tall grass, impermeable to water.