Regarding the role of the king and president
I just want to state that it is nearly impossible/inconceivable for there to both be a president and a king. I would suggest that restoring the king essentially locks in a pro-DNVP head of state.
You can tie the presidential elections to the restoration of the monarch too. "No one won the first round" "No one won more than 50% of the votes in even the second round" type of deal and then "we must denounce the republic for what it is, a sham which has failed to unify the nation and to garner the people's support" or "these elections are dividing the people and allowing the marxists into power with 30% of the vote" etc etc. And then restore the king via military/parliament's support.
What do you guys think?