A few questions re Generic Change Tracking

Perhaps somebody in the know can answer a few questions I have regarding
the Generic Change Tracking proposal:

1) Is my understanding correct that this proposal requires an infinite
number of attribute names to be added to ODF, ie. ac:change001,
ac:change002,...,ac:change999, ac:change1000,... ?

2) The wiki lists various use cases as "completed". Is the re a place
where I can find some examples for those use cases. In the moment I am
especially interested in deleting a column in a spreadsheet: say we have
a 100 by 100 sheet of cells. A1 and Z100 contain a 1 each. We are
deleting column C. How does this differ from deleting cell K100?

Thank you

Andreas