Yes, but this is very impractical since the spreadsheet can be very large and confusing for customers to use.
Yes, this is one of the options available to you.
A new vending key is generated for the new base date, still using the original SGC. Note that a KCT may or may not change the SGC – for example, you may go from SGC123456 to SGC123456, but only change the TI.
The KRN will change when doing the TID rollover in order to ensure that the meters keys change. A new vending key will also be generated to ensure that the meter keys are different.