I also love the Fantasy Nurgle Lord mini and again thought "hey I'll convert this for 40k". Fairly basic and my greenstuff ability is sorely lacking but happy enough. Painting Nurgle is very relaxing as I don't have to worry about being messy. :)
Hi man, the bases are resin and the finger prints are part of the casts. I'd smooth it out if I could, still not sure whether it's deliberate or not. Green wash isn't a bad idea.
Cool green stuffing. Make sure to smooth out those thumb prints (especially on base). Use more washes, maybe a green wash over the whole model at the end just to smooth out the harsh lines where colour bands are.