Do you have any plans to incorporate the modern era exp for VD?
no, my mod does include something similar though, so I do have many similar units to MEE.
(my main desire for Civ5 would be a modding system that makes it easier to pick and choose and combine mods, so you don't have to choose between different but equally good mods like this)
look no further than World of Civilizations then, it needs some time to mature, but that is what you will get from it
Also, although the new resources look really good, good enough to be in the original game, and I wouldn't want to see them go, would they not unbalance things a bit, in their global effects on heath and happiness?
they probably do

I was trying to think of a way round this, but couldn't come up with anything much (new buildings with negative health/happiness effects that the new resources are needed to counter? Or limits on the benefits you get from resources in the same 'category', e.g. if you have apples you get no extra benefit from having lemons as well, something like that?)
I won't include anything like that (as it won't be possible with just xml), so if you want to limit them, you might as well get rid of them imo as then the only thing they add is different looks.