Seasoning periods vary and it's not all that uncommon to find a lender that will allow 90 days, even NO seasoning if he can document the value add to the property (invoices, receipts, before/after pics, etc). 

As long as you have a detailed scope of work along with a contract, yes your contractor should be sending you a detailed invoice for any change orders.

Often, your personal time has no value to them, only materials or an actual estimate or invoice from a third party.

Of course, there will be expenses incurred in the business, however invoices should be provided describing what has happened.

I'm trying to buy a house and the underwriter is insisting that they need a copy of my current HOA invoice.  

Enter a maintenance request, assign a vendor, attach a fake invoice.

He emailed  me a week later asking for a credit card for the deductible and invoices/receipts  for work done. 

Are all my invoices uploaded to my owner portal?

Not every window can be fixed with a simple swap of glass.You should repair/replace the windows immediately and then present the tenant with an invoice.

Doctor, the problem is fixed, here is an invoice for $2000"The doctor looks shocked and says: "$2000!!!!