1: the list of ingredients is available online, look it up.
2: Drug companies
3: drug companies
4: Every working vaccine and medication is their track record.
5: Yes they do.
6: Months instead of years but based on a technology that had been in the works for years. Also Covid 19 is close enough to SARs virus that they could use the research that was started on that vaccine that wasn't needed.
7:Medical professionals, doctors and nurses.
8: Your doctor's track record? Well I hope you have a good doctor and not a quack.
9: It is very effective at lowering the severity of Covid and preventing death.
10: Is it required? No is it recommended?
11: yes all side effects are recorded, they are also listed on the same sites that have ingredient lists. Easy to find. Also you wouldn't know this but when you get the shot they make you stay for fifteen or so minutes to make sure you don't development any side effects.
12: All of them. If a large percentage of the vaccinated were dying because of the vaccine, say more people then die from Covid itself, then it's not something that could be hidden. Covid added five hundred thousand new deaths in 2020, before there was a vaccine. If the vaccine was deadlier then the virus one would expect many many more new deaths in 2021. It didn't happen.