1) What should I submit to Fenix?

To make testing your project more easily, please create a zip file with the whole unity project. Not just the scripts.

2) Shall I write a report about level5?

No, you don't need to. I just want 2 printscreens of Unity Profiler. The first one shows the method/methods you identified in the profiler as being the most relevant to optimize. The second shows the improvement in the performance of doing the optimization.

3) Do I really need to avoid all collisions when using RVO?

Using the current version of the RVO (and even the more advanced versions) it is really hard to ensure that there will never be any collisions when the number of moving characters is too big. It is up to each group to choose a reasonable balance between avoiding collisions and moving towards the desired destination. 

Also take into account that you can use different weights (you don't necessarily have to, but it is an option) for avoiding the obstacles and avoiding other characters (in the RVO time penalty).