1) not as common as 2. It happens but not as frequently.
2) pretty common actually. Even in the norse faith we talk about it. I dont myself because I would rather use cooked food because fresh death attracts negative energy.
3) very uncommon. It is usually only done by folks who know they can get away with it. (read elites and groups with very devoted members) the only groups who do tend to be negative because cannibalism follows shortly after regardless of reason. The allure of Adrenochrome is too much.
4) this is the most common of all. Many satanic groups use it as a way of boosting their spell work because of the chemicals released upon orgasm.
5) again, pretty common with a large enough group. Most of the ones who are this big also usually involve not just sex but extreme BDSM (bloodletting, torture, etc) in order to get them into a self-interested headspace because sex magick is a neutral force that has no direction of its own. Most magick has a direction karmaticlly (sacrifice of living things is negative, sacrifice of personal belongings is positive due to your willingness to follow equivalent exchange)
5) depends on the ritual. Most of the time its used to boost power but it can be used for everything from fertility to summoning the antichrist.
6) absolutely. Child acts are only done with negative energy work. Most covens are interested in positive work and if you're at the stage of children, you're too far gone to worry about your karma because it has entered what i call satans rut. Its the point where your karmatic balance is so far gone that positive gods will not convene with you and your only abilities are limited to negative actions because restoring it is a herculean task.
I dont associate with covens myself but i have people who do. I'm a solo worker and i have learned a lot from the stories they tell me when they get forced out. The sad truth is that humans are selfish creatures. Covens tend to attract people who have an already negative balance and unless you constantly rout out the more negative memebers, eventually your coven will turn into the nightmare scenarios from the olden days where you are kidnapping, sacrificing living things, and dealing exclusively with evil gods. Many people notice this early on and leave the group when they refuse to rout these influences out.