1.
if I add one to the Date it gives me date of the next day. How do I do it
for the days?
Example: 04-Jan in cell A1, on A2 I have =A1+1 gives me 05-Jan
if 'Sat' in B1, I want 'Sun' on B2 and so on.

2.
if possible I would like to have the cell B1 to show name of the day on a
date,
If A1 has 04-Jan, I want B1 to show MON or Mon and so on.

Thanks in Advance!