I want to integrate Misago to create a forum for an existing django project but I don't know what do you recommend:
- Integrate it through INSTALLED_APPS setting (is there any guideline for this?)
- Have it in a different instance
Excellent timing, next release is focused on integrations with existing sites, and work is well under-way on this ;)
Have it in a different instance
This is the way to go. Misago is a very complex application that has many dependencies and makes a lot of assumptions/architecture decisions. Trying to get it integrated with your project on code level means you will effectively have to maintain all of this + your own project.
The recommended way is to setup Misago on a separate instance and use the SSO feature that will make Misago delegate registration/login to your site. You will only have to add SSO server to your Django project for Misago to connect with.