Hey Reena,
The cross legged position is awesome just make sure your posture is good, You can all so do seiza where your legs are under you and feet are crossed. If you don't feel like either of these suit you go to lotus where your feet are both laying on your thighs. It kinda looks like cross legged. Posture is an important thing in energy. So is water they are both keys to perfect harmony in energy.
The CKR I don't know but I get where you are going. CKR is already built in with 3 circles. Some people like to change the circles to go clock-wise. Do what your intuition on that.
The do's and don'ts are simple. A thing that I stress on my students (if i had any) is to disconnect this is an important thing when healing others. My Qiqong instructor explains it as this, "Its like having sex with someone with stds." When you do not disconnect you are leading into self inflicted psychic attack. You can tell if you are still connected by telling if your energy is being drained. Just do a quick karate chop inside your aura as a visual and say I disconnect from those who are hogging my energy and it is done. Grounding, Make sure you are connected to mother earth, She is a great companion while healing. Also brother sun he helps to.
Reiki Blessings,
Grandmaster Alex
Midorimasu Reiki