Hi Henriette,
Welcome to the forums! Most of what you’re asking can be found amongst the Medications section here but I will say for my part, Ritalin has few side effects while it’s working but I do tend to get headaches, tiredness and irritability when I come down from it. I’m taking 10mg/day of the instant release version. The extended release ones I’ve heard have the same effects only the meds last longer. I’ll be switching to Adderall XR soon though…
I hope you find answers to your questions! Try not to dismiss the meds without first understanding what benefits they impart to people who need them (which is exactly what you’re doing! 
)