1. To create a mixed terrain, press Shift while adding the secondary terrain. For example, to create forested snowy mountains, create a snowy mountains hex, choose a forest terrain and then Shift-click the snowy mountains hex.
2. You can add named locations (see location_id in SLF) by using the starting positions tool and clicking Add. A dialog will prompt you for a "New Location Identifier", which will become the location_id value.