To replace commas with newline characters use this formula (assuming that the text to be altered is in cell A1):
=SUBSTITUTE(A1,",",CHAR(10))
You may have to then alter the row height to see all of the values in the cell
I've left a comment about the other part of your question
Edit: here's a screenshot of this working - I had to turn on "Wrap Text" in the "Format Cells" dialog.