And the first one is how we can display new informations on the map, or even edit the map as a consequence of the actions or discoveries of the characters.
The easiest way is to add a floating label that points directly to the place that you want to mark. The advantage is that you can add as much text you want into it. The drawback is that if you have too much of those labels, they are going to make the planet map very confusing.
Anyway, they are easy to make:
-Choose the label tool
-Click on a point on the map and extend the label to its position
-Fill the text in the label
It is also possible to draw directly on the texture map that covers our 3D planet model. Indeed, Sketchup has a function just for that.
-step 0: before being able to use that function, you need to have a graphic program linked to Sketchup:
-Preferences>Applications and choose a graphic application like GIMP or Photoshop
Now, you can edit your map, from Sketchup, on the fly:
-step 1: right click on a face of the 3D map, choose texture>edit texture image and it should open in the program chosen in step 1.
-step 2: make the modifications to your map in your graphic program. Hint: if you are making a change on your map because the players have discovered that their map was inaccurate (there is a city where their map indicated a forest), a simple copy and paste from another hex is quick enough.
-step 3: Flatten the image and close it. When the program asks to save the changes, click yes.
Given the size of the mapping texture, it won't be possible to add many informations onto the hexes. At best a symbol of two or an index indication directing to a note in your scenario.
But, whatever solution you use, it won't be possible to map the planetary 3D model with the details that could be needed once our characters are on the ground.
You'll find a lot of advice by reading the articles about hexcrawls that were posted on The Alexandrian blog, more to the point that I could hope to write.
Anyway, to map those hexes, you can go back to Hexographer, Tiled (a post about that wonderful program is long overdue) or sketch them on paper.