You know what I would suggest? Rather than having the two ADOTables, have a DBTable in the stores of what the database table looks like before the update. Then, run the update and run DBTable.Compare. That would effectively do what you're asking without having to write any excess code.
On your other question, yes, it is possible to write code to export the table data to a file for file comparison. This will take a bit of code to do so, but it's not difficult stuff.
Feel free to ask for help if you need some guidance as you write.