1) Not everyone can cook, but great cooks can come from anywhere. SWE @ FAANG is a high bar, not everyone can reach it. Being older will make it more difficult. But it is not impossible and the only way to find out is to try.

2) Given you have no prior CS background, I would recommend finding a undergraduate / graduate program. I would heavily recommend internships / part-time work as a student. The easiest way to get into FAANG is via return offer for internship. You should practice SWE interviewing and prepare a lot for those interviews, they are a big blocker for many roles, and interviewing techniques are not commonly taught in university.

3) Depends on if you want to do research or engineering and how good you are. I don't think you should worry about this problem now though, you aren't at the stage where specialization matters. Just learn about what interests you.

I think if you're serious about your goal of making it into FAANG, the best-case timeline would be ~5 years. I would break down your goal into smaller ones (Graduation, first internship, first job, etc) along the way to maintain momentum.

The game is definitely worth the grind financially though. Best of luck!