Hi, as someone who did their IRP last year, here is my input:
• for a rough idea, choose a feature of French culture that you're interested in. For example, is there a political topic you'd like to discuss, or a more generic topic such as history or music that you would like to delve deeper into. Personally, I wouldn't choose a question based on an historical event, as it's harder to find enough subheadings to cover it unless you can find something lesser known and more controversial (for example the impact of French colonialism on a specific colonised area, or the controversial life of a key historical figure and how this is still relevant today).
• don't pick a topic that you can't find 5 subheadings to accompany it. Those are what really matter as they'll be what you're questioned on and what you need to cover in your 2 minute speech (which is what the questions the examiner asked are based off). Avoid choosing a topic for the sake of having fewer subheadings as you'll have less material to talk about. Getting cut off because you've run out of time in your exam at the end is better than finishing your supposedly a two minute speech one minute in.
• I know this is obvious, but there is more to the francophone world than France and Belgium. There are so many opportunities to find a topic which isn't generic or canonical to each year (cue the French Revolution topics) - you can literally just type in a francophone nation and look at recent news headlines for inspiration - look at Martinique's controversial path towards recently getting a new flag and anthem, or the impact of the French Foreign Legion on overseas territory. Look at the role of the French language in these countries aside from native languages.
as for the topics you've listed (this is my personal opinion based off my experience):
• Le Mans looks good. It doesn't matter whether you've covered any history of not (in my opinion it's a flaw in the spec to not have any); as long as it's solely a francophone event (which it appears to be) then you're fine. just ensure that it is analytical and not pure facts. the facts and stats back up your opinions and help you to develop well-phrased answers to questions.
• you could do something on LPP/Saint Exupery but you'd have to ensure that you don't spend your speech describing the plot, nor giving a straight analysis of the book as this is too generic and frantically boring. Unless you can connect it to a real event or its impact on French society in multiple ways then I'd give this one a miss, or I'd certainly choose the Le Mans topic over this one.
• traditional food is too farfetched and generic and you'd need this to sound more honed in and analytical rather than just listing and describing and using each subheading as a region. this sounds too explanatory and I wouldn't do this unless you choose a single item of food and go into detail on its influence and role in French culture without being too descriptive.