If you need to ask whether the file is text or binary, why not use the .osm files instead.
Also, to add to the comment about variability in detail,detail can very on a scale of 10s to 100s of metres, not just on a national scale. For a feature to get mapped, someone who has an interest in that feature needs to take interest in an area.
osm.pbf is bynary format, but heavy based on key-values what comes from XM world.
You must use Google’s protobuffer library to read internal structures.
Planet.osm.pbf not contain any indexes, so if you want “find near objects”, you need to process around 36gb of data.