Populate Drop to Surface
By default Populate doesn't allow you to have your characters walking on uneven surfaces. This MCG hacks a way to put them on any surface below. It's not perfect but it'll work for a lot of cases.
To use this, install the MCG package, it'll make a new modifier called Populate_drop_to_surface in the modifiers list. Apply it to all of your populate people. You can apply it once and instance it to all of the others. Pick your surface and then you normally have to do a small offset to make them sit a little better.
Now updated to work when the Populate flow isn't created at 0 height in the Z Axis. You have to pick the Flow node for Populate as well.
To network render you either need to 'include maps' or have this MCG deployed to your network or in a network location. Ask Mr Google for help with this.