It is not possible to change the width/lenght of a single cell, but only of the whole column/row. As for the rest, it is possible to edit more cells at the same time only by selecting them before doing the edit, and you can select multiple cells only if they are close to each other..
As a general rule anyway, it is always better and quicker to copy-paste from a similar table and then edit what you need to edit. For any specific request don't hesitate to contact me in private, I am quite expert with tables editing