I think the priority needs to be on separating testing and development from production, and you can worry about mxiing ETL into production at a later date. Just getting production cleaned up will be a large effort, no matter how small the organization or enterprise. It's amazing what the passage of time can accumulate. Just documenting what's already there is task one, and that will quite likely take far more time than you might be willing to believe. You may even find yourself with code for which there's no source in your .NET side of the house, or, make the revolting discovery that the deployed code is actually significantly different from what you thought was the documented source, and thus that said allgedly correct source, isn't correct; just after deploying an update that used the allegedly correct source, only to discover that you have no good backup of the previously deployed, properly working, code. That leads to task two: Don't change ANYTHING until EVERYTHING is documented, and most importantly, VERIFIED. It's always amazing just how many dependencies you discover AFTER something changes. At the very least, be 100% sure you can go back to the previous state of affairs before making changes.

Hope you find it all.... and good luck with your efforts!