As for your second objection: that the multiple return of the soul to different bodies—with varying inclinations and formations—implies that the number of souls is fixed and limited since the first creation, without increase or decrease. You argue that this requires an explanation for the population increase, and that claiming the number of souls is limited is an attempt to restrict God's power and "freeze" it in a refrigerator.
The Response:
Seeking aid from Allah, we begin with the words of the Almighty:
{Praise be to Allah, Creator of the heavens and the earth, who made the angels messengers having wings—two, three, and four. He increases in creation what He wills. Indeed, Allah is over all things competent.} 1
The verse is explicit: Allah increases His creation as He wills.
Because the craft is nullified and perishes with the death and perishing of its owner, while Allah, Blessed and Exalted is He, is Ever-Living, All-Sustaining; neither slumber nor sleep overtakes Him.