I can't give you much help except I can tell you what I thought about your film choices. I've used Velvia and I personally hated it, the times I used it my greens (from leaves) just looked really bad (my metering was good and a professional lab developed the film too). I've also used Astia, which I found to be a much nicer film; it still has good saturation and colors but not to the unrealistic degree that Velvia does. However, perhaps Velvia will work better for you, I'd at least give it a try. Considering that you've bought two new camera systems and are looking at a scanner and a computer, a few rolls of Velvia bought and developed really wont cost much.
Personally I prefer Agra RSX 100, I found it to have very nice tonality. However, that was when I was shooting architectural (interior and exterior) shots, not exactly what you're doing. If I can't use the Agfa films, then I use Kodak slide film.
You might want to try Kodak EPP 100. I have yet to try it (I will this weekend) but I was told by an incredibly knowledgable chemist/photographer/alt. process printer that it has a lot more exposure latitude than any other slide film, except for perhaps some tungsten-balanced film. In the landscapes I photograph there is quite a bit of contrast and highlights are often blown-out if I want my main subject to come out O.K. A slide film that can remedy this seems particularlly appealing to me...