Licensing my app made with third-party packages and permissive assets

I have an app made with electron.js

• I have used third party packages in my app.
• All the packages have permissive licenses(MIT and BSD License) with them.
• I am using UI assets(e.g. icons) with permission based on promise to credit them.

I want to license my app with MIT license

Now my questions are:

1. How do I license my app. Is it just as simple as adding MIT license copy in my repo.
2. Do I need to do something for third party packages licenses (for both packages dev and dep).
3. Some assets owner/authors did mention that I need to credit them in project. So how do I handle this, do I need to make a file with all their license and credits.