If a POG, awarded with a CAB (combat action badge), were to transfer to Infantry, would the soldier be authorized to wear the CIB?

No

The bottom line is is that if an award is not annotated in your personnel file you're not allowed to wear it. For many years I wasn't authorized to wear a foreign award I legitimately won because it wasn't in my official file, I finally got someone in S-1 to place it in the files after I provided the substantiating paperwork.

Do you want to get your ass kicked? Because that's how you get your ass kicked!

If you mean a member from a sister service who engaged and closed with the enemy in combat, no. You take POG and stick it.

NO

Thousands of "POGs" have tombstones marked with KIA. Likewise, other thousands have Purple Hearts. I despise us of the term.

No, only the CAB would be allowed unless the service member is awarded CIB/EIB while in the new role.
Only one of those badges can be worn at the time though, as far as I recall.

No, he would still wear the CAB until such a time he gets awarded the CIB (or EIB), only one badge would be allowed at the time. As far as I recall.

No.

The main requirements are (1) you are assigned to a Infantry / SF Unit ( 2) You have them lil Metal Bee's whizzing past you , On a side note it's preferable that you do not attempt to catch any of them lil metal bee's .