Hey mate - i think he looks great!
I'd personally like to see some more rust/corrosion on the scythe, plus some oxidisation on the brassy coloured areas to give him that really old and corrupted look.
But otherwise you've nailed the bleakness of Typhus
For bases - it depends on if you were going to be doing it yourself or buying bases.
if you want to buy some to paint you can't go wrong with the corpse field bases from Secret Weapon miniatures
http://www.slavetopainting.com/products/basing-terrain-conversions/scenic-bases/40mm-bases/beveled-edge-40mm-corpse.aspx
Also, from the same manufacturer, there's the blasted wetlands or bone fields bases. All would be a great choice for a Nurgle army.
If you're doing it yourself then maybe something muddy with some puddles of slime made using some water effects stuff and green paint, or just green paint and gloss varnish over some PVA. Could look really cool.