Chance of an English speaking taxi driver in port?

We would like a taxi to the rainforest and Mt Pelee. How readily available are taxis especially English speaking drivers? What about US dollars??? If we need Euros, how much do you recommend we have for 3.

We are not finding many excursions that interest us from the Jewel of the Seas. Of the two we like, our son isn't old enough for one, and the other is very expensive.

Thanks.