I understand your frustration and like all frequent travelers I have had my share of delayed flights, missed connections, delayed luggage, long immigration lines and the like. Unfortunately these things happen with any airline, even SQ, CX or the like.
The title of your thread is:
Advice how to proceed for some kind of compensation after 'horror' flight

So let's be concrete and try to answer that.

As suggested above, the best is to write a short and factual (non-emotional or threatening) letter.
The compensation that you are legally entitled to is the "right to care" and some possible financial compensation. The airline "cared" by providing accommodation and vouchers for dinner (you were also entitled to two free calls). The question of legal financial compensation is always a sensitive one. But it would be likely that AF will claim extraordinary circumstances not under its control as there was an ATC strike. So, they would have a strong case to refuse compensation under EU261. But you can ask anyway setting your expectations low.

So, you are left with hoping to get some commercial gesture from AF, which they should provide. You did get into a lot of trouble but that is totally at their discretion. To me, that is the best avenue to get some compensation. However, you seem to hold no elite status, and airlines tend to be less generous for an occasional flyer. If you insult them and tell them that you will never fly with them again, they will be less favorably inclined.