[X] Focus on locating Hermione and ensuring her safety
[X] Protecting those he has been assigned to
Focusing on the mission here.
Shinji will do enough damage just getting to her and protecting the VIPs. The building does not matter. Killing the enemy does not matter. This is a war where the idea is to not ground the enemy into dust but to win by winning the hearts of the people. Albion has talked big about protecting the people when the Ministry could not, so it is time to put the money where their mouth is and protect the people, starting with Hermione and the people that she herself would gather in the hopes of protecting them in turn.
Buildings can be rebuilt. Enemies can escape to fight another day. But people can not be replaced.
The first choice has a bunch of good actions but really we need to find Ms Granger ASAP. Once she is found, THEN we can consider what actions to do to help keep her safe and turn the tide of this fight, like reinforcement of rooms.
Rather than trying to protect the entire building it would be easier to protect a smaller part of it and focus your forces in that smaller area. Trying to protect everything will mean that you wear yourself out and protect nothing in the end.