I'm inclined towards Thunderclast being Tension-Fused. Mostly because I believe Renarin has access to Tension and that is what he used to disable the Thunderclast.
If we didn't have confirmation that the Stormfather is merged with Honor, I would put the Stormfathers/Highstorms alignment more towards Odiums notion of himself as Passion.
The difference I see with the medalion and the primer is that the primer/ettmetal essentially gives the ship a 'singular soul' which then perhaps another mechanism grants/affects the ships allomancy.
I'm probably wrong though.
I would think the corruption allows the Oathgate to be used to get in and out of the CR. It doesn't need to be un-corrupted to function for PR transport.