NOTAMs and Weather are downloaded direct on the device. This requires that your device have its own internet connection. If it doesn't, you can't get NOTAMs and Weather in InFlight.Terrain data is not drawn on the main map in InFlight, only in the Approaching Features instrument.
Data updates are just copied over when necessary; they are simple files. We'll be introducing a tool to automate this process in the near future.
You set it in the NOTAM filtering window, in Plan. In InFlight there is no setting for this; when they are downloaded the next whole day's worth are always displayed.
Better than TAFs?