1.Are the wealthy experiencing dukkha in a different way to the poor?
We all experience dukkha differently depending on our karma.The wealthy can afford to experience happiness born out of sensual pleasures than the poor.
2.If so, in what way? Are they experiencing it in a more / less refined way?
How refined their dukkha is depends on how strong they attach to the happiness their wealth brings to them.The more they attach to it the more painful their dukkha is the less they attach the more subtle it will be.
3.What did the "Buddha" say about money and suffering?
Money or wealth does not bring suffering.It is our strong craving/attachment to it that brings suffering.Wealth is actually in a way kind of like a blessing.It is one of the karmic resultant of practicing generosity in previous lives and the result of being hard working and industrious.The Buddha often instructed lay people on how to preserve their wealth.And in the Adiya Sutta even describes the benefits to be obtained by having wealth.Adiya Sutta:Benefits to be Obtained from Wealth So don't see money or wealth as a cause of suffering.you can easily substitute the word money for anything under the sun and the only way it will cause us suffering is through our strong attachment to it.