Venom Coating only coats one of the weapons. I would not take Geomancer with Scoundrel, it's not a good fit. However, Aerothurge has a number of support skills which are very good for mobility and enemy manipulation when paired with Scoundrel, like Teleport, Nether Swap, Favourable Wind, Uncanny Dodge.
I chose a Dwarf for my Rogue, the additional health and evasion chance can be helpful. I'm already at over 20% chance to dodge and I haven't left Fort Joy yet.
