[Deployment Automation Manager] ddl_path/flyway_path related questions

Hello!

I'm on my way to create CI/CD process for our Appian developers team. We have several environments (Dev, QA, UAT) and now we migrate apps from one to another manually, also we have to execute sql scripts to create schemas in related databases for environments manually too.  
So, we've decided to use Deployment Automation Manager. I've carefully read documentation article, and got how to put applications to Git and then build packages and deploy them on next level environment. But I've got several questions left.
First, do ddl_path and flyway_path alternate each other? Are they just two different ways to migrate DB related stuff between environments, or are used for different purposes (like just tables creation and/or data contained in these tables migration) 

And the second question is related exactly to ddl_path option. As I noticed, DDLs that I download from Appian UI have update section and drop-and-create section. And the second is commented out. So, the question is, should I uncomment it before putting to Git, so import manager script could execute it, or, I should run drop and create manually, and leave this section commented.

THank you!