If my bank and insurance accounts already have POD and beneficiary instructions, do I have to list each account with instructions in my Will?

You do not need to list all of these accounts and policies in your will.  A "pay on death" (POD) account will be paid to the beneficiary outside the estate or will.  Only if the beneficiary is your estate, will the proceeds be paid to your estate and pass according to your will.

This is an important point for everyone.  The POD instructions are followed no matter what the will says.  If you want to change who receives the proceeds of a POD account, you need to change the POD instructions.

In my practice, I always inform clients about a living trust.  It is not that expensive to create one.  Once the trust is established (and funded - it can be funded with a token amount; I recommend that clients open a trust checking account with $100), then all the POD accounts can be made payable to the trust.  You could distribute the proceeds any way you like via the trust agreement. A trust is managed outside the estate and not subject to the will.  It does not require probate.  (If you have a taxable estate - currently in excess of $5 million - be sure to get advice before using this option).

There are many choices for life and estate planning, and they all have consequences.  It is a good idea to consult a lawyer to draft your documents.  A lawyer can make sure that your documents achieve your goals and avoid unintended consequences.