Deductions for business use of home from many years ago

I am planning to retire in the next 2-3 years. At that point, I will sell my house and downsize. Since I have lived in my home since 1993, I have made a lot of improvements and kept all the documentation I need to justify the improvements. But instead of patting myself on the back, I feel like a total idiot because I have not kept the original closing documents. Also, I claimed deductions for business use of my house (1993-2010) -- and I have not kept my income tax returns for those years. (I was not using TurboTax at the time.)

 

From my county property tax info online, I have found the original price I paid for the house. Now I wonder:

 

1. Is this information the only one I would need from the closing documents if I had them, or would I need more info?

2. If I do, how do I get a copy of the closing documents? I don't remember where I banked when I got the loan, etc.

3. How about the deductions I claimed for the business use of my home office? How can I justify them? Would the IRS provide me with this information?

 

Maybe I should just keep working until I die and let my heirs figure it all out! Thank you for any help and reassurance you can provide.