Would I be required to speak near perfect French?
Depends what you mean by perfect, but if you intend to study as an undergraduate here, then you do need to speak good french because english courses are mostly for masters+.
What should I study in university that will allow me to live a very comfortable life in France?
Maybe some people will disagree with me, but I think that if you move here (so without a good professional network) I would argue the school you go to will be more important than the subject you study. The reason for this is top schools provide better internship or job opportunities and have higher salaries for same jobs as people who come from "less prestigious" schools.
You should aim for "Grandes Ecoles" HEC, ESSEC, EDHEC, EM Lyon ESCP Europe (those would be the top business schools), Polytechnique, Les Mines, Centrale Paris, Supelec, Supaero-ISAE, Telecom, Ponts et Chaussée etc (these are some of the best engineering schools the 3 first I listed, especially Polytechnique being the most pretigious and known worldwide).
Sciences Po if you want to do a more social science oriented school.
Obviously you can do other schools and land great jobs that pay well but with these you have an easier time getting those jobs (strategy, finance, etc) and they have powerful alumni networks.
You should know you can't access these schools (except for Sciences Po) right after high school, you need to do at least 2 years of intense prep school. Universities are good too but it's just harder for some people because you aren't supervised very closely.
I know in the US working in the tech industry as a software dev gives a good salary, however I am not sure how true that is in Francee but I know alot of people here are devs so they might be able to talk to you more about this.
Also you should be more clear about what you mean by comfortable. The same salary won't buy you the same comfort of living depending where you live. The schools I listed though you get you something between 35 and 45k per year in your first year depending on your job. Paris is pretty expensive so if you value quality of life, then for the same salary you can live much better in other big cities in France.