1)You can start helping right away. There is an aspect of SFQ that is immediate. Calling on the masters energy is important. You don't have to know or feel what you are specifically doing, by doing that, but doing it in a respectful way brings in additional energy, along with universal energy. You can experience this, or explain it as a spiritual aspect of qigong, or simply go through the motions with positive intentions and let it work for whatever reasons it does. Your desire to heal someone and be open to receiving additional energy to do it, makes it happen. I find SFQ unique in how it breathes in energy, in comparison to other qigong systems.
2) I have taught in the past. I had some people who came for my energy, and didn't work on their own self empowerment. They felt motivated, and did their best practicing, when with me. I eventually felt this as a loss of energy. Almost like I was doing the work for them. It is important to have your own time in the exercises, where you are focused on healing and/or energizing yourself. When you work with other people, be aware of your own energy and boundaries. Help someone else help themselves. Be prepared to give when you are with someone, helping them. Teaching/helping can be very similar to healing someone. Be aware of your breathing and your connection to the universe and "master's energy, in the sense of replenishing yourself, help them help themselves, bring in energy as you put out energy.
3)I don't think one ever masters a system in the purest sense. There is always something more to work on and learn. Qigong study compliments martial arts. Tai chi is fine. Master Lin practices Tai chi. You do have to give them their own space and time. You can practice qigong and continue martial arts. I do find that SFQ is very focused on healing work. Occassionally I will practice a martial arts form or exercise. I try to do it purely as a physical exercise, to invigorate that part of myself. Some martial arts practice can be very connected to warrior energy. You may walk around imagining fights, blocking punches , etc. Maybe picturing yourself jumping that terrorist in the airplane! This is not necessarily bad, but there are higher level thoughts to encourage, and hopefully manifest.If a question arises concerning your present situation regarding what you are practicing, it may be for a reason. Be open to change, don't lock yourself into a direction that may not serve your best possible growth. You can try something and not feel like you have abandoned your intentions of mastering something. Starting over in something new can be very self empowering, your experience comes with you, and you gain new insight. Listen to your heart in making decisions.
4) I am not sure what type of cell.He did respond well to chemo and radiation, living a good year past projections. He did have alot of special people giving him energy though. Master Lin said that cancer cells are very thick walled/closed cells that don't communicate with the body. They are addictive to self growth. Medicine doesn't penetrate the cell wall. The mind, can penetrate the cell and put in the right information, (this is not good for the body, go back to the universe). Again, this is signal healing.