Oliver Hazard Perry leader counter from Amateurs, To Arms! by Clash of Arms Games.
Warrior Band counter for Conquest of Paradise by GMT Games.
In the pre-move i can cross a known Hex but is a discovered Hex face down with mine discovered Island-Marker on it a known Hex?
If you want to pre-move your Explorer over a face-down Island Tile that you have discovered (with your Discovered Island marker on it), you must flip the tile face up. Yes, now everyone will know what it is. You might want to reconsider where you start your Exploration!
...return only a Hex back or return completly Home?
Actually, return completely by placing the Explorer in front of you. (See the last line of rule 6.4.) Your home islands can get pretty crowded with villages and pieces, so it's easier to just keep your Explorer off the map and in front of you. Next turn, simply place your Explorer back on the map and start your pre-move and exploration. Unless, of course, your Explorer is in the Lost box!
Hope this helps...