A list connected by and indicates that all of the elements in the list are expected to be included.
Jack and Sarah will be here.
The use of and indicates that both Jack and Sarah will be here.
or is a little different. The use of or indicates that not all of the elements of the set may be involved in what is being discussed.
Jack or Sarah will be here.
The use of or indicates that one of the two will be here.
We will go by car or by boat.
One of the two modes of transportation will be used.
We will go by car, by train and by boat.
The use of and indicates that all three modes of transportation will be used.
or does not always indicate that only one element of the list will be involved, but and always indicates that all the elements will be involved.
Jim, Susan and Fred will be here later.
The use of and indicates that all of them will be here later. The meaning of that sentence clearly excludes the possibility that not all of them will be here later.
You could get help from Nisha, Andrew or Monique.
While strictly speaking that sentence means that you could get help from one of them, the meaning of the sentence does not exclude the possibility that you could get help from more than one of them.
Regarding and and &, & means and. There is not really any difference.
