People don't like negative feed-backs but I place the bid just to tell you some bad points in your requirement:
1. Most Arduino libraries are in C++, include many from the links you provided. C is impossible.
2. Why JS client need to get RTC from server every seconds? Every client has clock and just need to sync time with server at minimum hourly.
3. Upload [login to view URL] is good idea but make the system more complicate. Easier way is - gzip the html, js, css files, added it as part of the code and flash all (code + web) together via OTA, so no need SPIFF.
Please also notice that ESP8266 supports maximum 5 concurrent connections.
Well, about me: I am not speaking French. Technical skills: I did a lot of projects with the requirements similar to Job 1 and if you need, I can make a demo for you.