Tool to generate a comparative analysis about a topic on social media

Dear community,

I am a student in journalism and I am currently writing an article about politics on social media.

I would like to compare the social profiles of 5 politicians in my country (France) and see which topics are the most relevant to their social profiles. In order words, I would like to know what topic they mention the most.
For instance, I would like to know which topics are talked about the most in François Hollande's Facebook and Twitter pages.

I would also like to compare the importance of a given topic for each of them.
For instance, I would like to know whether Hollande talks about sustainability or security more than Sarkozy does.

I would also like to compare the weight of different topics on social media. For instance, I would like to know if "sustainability" has more mentions on social networks than "security" or "unemployment".

Preferably, I would rather have free tools, since I won't get paid for this study.
Also, it needs to be able to analyze French content.

I there is more than one tool, or if a tool can only help me through one or two of my goals, that's fine.

Thank you very much for your help!