There are some side effects for both oc pills ans well as nuvaring
.There may be irregular bleeding,weight gain,low back pain
etc. as side effects.Only difference is that you will have to remember to take the pills every day and nuvaring is only introduced once and valid for a long period.Different people tolerate side effects in different ways.If you cannot remember to take the pills then nuvaring might be a better idea for you.
To answer your second question,regardless of when you have sex,you will need to take the pills as prescribed.Otherwise you wont be protected.