Pattern the key. Just like some people are tall and some short, some introverted and some extraverted: every baby is different. Starting around 28 weeks, you should do kick counts at night, while in bed, right before you are about to go to sleep. Soon you will get an idea of what is normal for your baby. If you feel the baby's movements are less than what you have learned to expect then it is of significance.
This varies. A quick and simple fetal kick count method is to focus on counting for up to 2 hours and tallying 10 movements in that period. '10 movements in 2 hours'. Babies move throughout the day, with movement peaking at night. The quality of that movement changes as the baby grows and periods of rest also change.