Yes, although ideally, you want to be over 18 years old. You also want to talk with a medical expert to ensure you use the right body massage machine to fit your needs.
You can use it a few times weekly, depending on your feelings.
Some machines are not great for pregnant women. Also, they might have counterindications, so read those before picking a specific machine.
You don’t want to use any lotions or massage oils with these machines. Unless, of course, the machine allows that via its indications and guidelines.
It depends on the intensity of the machine. Some machines have very high intensity, which can be an issue.