Compiling a list of data into one cell

So I have a list of names in one column, each in its own row/cell. How do I compile all of the names in the column into one cell so that each name is separated by a comma?

I know I can use: =a1&", "&a2&", "&a3&", " and so on
But I am wondering if there is a way to dynamically have this done... so that if more names or added to the list then it is automatically added on in this format.

Also, is there way so that if a name in the middle of the list is deleted, than names below are moved up to fill in the gap?

Thanks so much if anyone could help.