B-I-N-G-O

The counters are considered to be on the inherent tracker in B-I-N-G-O's art, not on the creature itself. Those counters can't be removed or moved to another permanent. Similarly, if you proliferate, you can't add more chip counters to B-I-N-G-O.

All nine rows count. You can fill rows horizontally, vertically, and diagonally. A full card with give B-I-N-G-O +72/+72.

Casting multiple spells with the same mana value has no additional benefit. Once a spot has a chip counter, it's marked, and additional chip counters won't do anything.