Theres no trick to climbing the Dragon just jump towards it and while in mid-air time your "grab" move as you come into contact. Make sure you have enough stamina like any other climb.
Id say not to bother with higher level pawns. The RC cost / advantage ratio doesnt seem to add up and there are better uses for RiftCrystals later in the game so id save them personally.
You encounter PortCrystals as you go through the game that act as WayPoints. After picking them up into your Inventory you just use them at the spot you want to create a WayPoint at. This means when you use a FerryStone it will now have that PortCrystal as an option of where to "teleport" to from the list. I think theres about 4 or 5 PortCrystals in total, but you can always pick them back up again to move them later.
Remember theres certain quests to pickup in the world, not to mention that become available after discovering certain areas so it pays to wander around