Also, just a quick thing regarding Aizen's strength. After he was beaten by Ichigo and Urahara, and sealed away temporarily, he lost access to the massive power it granted him such as:
-Fragor
-Mountain busting sword swings
-Teleportation
After this chapter people are speculating that he, in his current state, is more powerful than he was back during the FKT incident.
His powers are implied to have grown over time, even if only slightly.
Urahara doesn't know how to remove the Hogyoku from Aizen. He created a Kido to seal Aizen since killing him is now impossible, but he developed nothing to remove it from him entirely.