There is a separate wood aging subforum here that might have a lot of info you will find helpful: https://www.homebrewersassociation.org/forum/index.php?board=30.0
There's good information in some of the homebrewing books and magazines although I don't think there is a definitive guide--even at the pro level. I would encourage you to read what you can before you acquire the barrel and before you put beer in the first time. Barrels are sensitive environments not like your glass, metal or plastic fermentors. Once the wrong element gets into the barrel it's nearly impossible to get it out. There are particular cleaning and care regimes you need to follow, especially if you plan on using the barrel more than once.