I have a line of credit that was originally $1,250,000. We just decreased the limit to $1,000,000. Normally, I would not report a decrease in the credit limit; however, in this case, since it is now <= $1 Million, would it be reportable???

Yes. You would report a line of credit for $1,000,000 as a small business loan as long as there was nothing that would disqualify it from meeting the definition of a small business loan (such as a lien on residential property with residual collateral value in excess of 50% of the loan). You report the line amount, not the decreased amount of course.

If I had a loan for $50,000 that originated in 2008 and was
renewed it in 2009, but the renewal has been reduced to $40,000, would I report the reduction?

Thanks!

Yes, report $40,000 on your LAR. However, if the renewal and line decrease occured in the same year as the origination, you would only report the origination.

Would you use the earlier date of the renewal, or the later date of the decrease?

Earlier date of renewal - assuming you mean a loan renewed in a calendar year (originated in a prior year) and subsequently refi'd at a lower amount.