Hello George, We have not had writing on our board for days or weeks at a time so I cannot address that portion of your question. However, I can tell you that the board erases completely with the eraser we have which is a 3M whiteboard eraser.
Reasonably recent writing (I'd say anything left up to a month or less untouched) erases nicely without need for cleaning fluid. Writing more than a month old, particularly in black, may need a little fluid help.
We use our board to track data in our business, so it stays up a month at a time. We love the board. Most of the writing comes right off, but I do also keep a bottle of the spray at the board---it takes it off right away, no elbow grease needed!