I’m back from the break 
Here is current state of Havok physics for your concern:
Heightmap terrain shape is in progress. It should be merged by End of Feb, just before 7.0 code freeze
you can do axis lock this way : setAngularFactor for Havok - #3 by Takemura
No ETA for Kinematic Character Controllers and Raycast Wheeled Vehicles yet. It’s something we want to do for quite some time and as usual, prioritizes change.