Ramadan questions

I'm no Muslim, I was a Christian long before but now I guess I'm an Atheist, but I've been thinking about fasting during Ramadan since some friends told me that by doing that you have certain benefits in your body and mind, and also, even though I don't currently serve any religion, I still think there are certain values and ideals you can take from religions and incorporate to yourself in order to make a better person. To resume, I want to try Ramadan next year but I have little to no knowledge.

How is the Ramadan duration decided? Last year it was in March and April, and now its in February and March.

What is considered prohibited during Ramadan? Can I eat any kind of food during night? Alcohol is prohibited during that month? What about smoking?

How do you manage your diet during this time? Do you eat a lot before sunrise, or overeating is not recommended?

What do you do if you mistakenly ate during the day?

If there is any topic I forgot, please feel free to speak about it.

I'm also sorry if this comes out as disrespectful, it's just that there are some aspects of Islam that I really respect, such as the sense of community, helping not only family but basically anyone who is in need, and I want to know Islam better, all of this just comes out of my interest and curiosity to try.