How to move around in formula with arrow keys on excel for mac

Man, I'm just starting to use excel but please help.
in formula, if I command + shift + down to highlight all data and command + delete to come back to active cell, I can't move my arrow key left or right to select more data set. I have to use my cursor to do so.

and if i push enter after the formula, the computation doesnt show up right away. i have to mess with the column width just to see it.

Am I tripping or is this a bug? please help.