Here's a list of a methods that will probably save you time and sanity. Please let us know in a discussion if there's anything we can do to make your life easier.
Getting the first/last row/column/cell is a common task. Instead of specifying it manually you can use any of the following methods:
range.FirstCell()
range.FirstCellUsed()
range.FirstColumn()
range.FirstColumnUsed()
range.FirstRow()
range.FirstRowUsed()
range.LastCell()
range.LastCellUsed()
range.LastColumn()
range.LastColumnUsed()
range.LastRow()
range.LastRowUsed()
You also don't have to calculate the range used, just use the following. You can also use it's overloads to specify whether you want to count formats as cells used.
worksheet.RangeUsed()