-If I’m using for example a sterex two pice stainless needle, how many hairs can I treat, and with a Gold?
One at a time with any type of needle unless you have a multiple needle epilator.
-What are the advantages of the insulated and gold?
Gold - Will help people that have adverse reactions to nickle which is in stainless steel in small quantities.
Insulated - Good choice for thermolysis. A newbee can really cause damage with thermolysis if you overexpose yourself. Insulated probes will focus all of the radio frequency (RF) or short wave frequency (different name, same thing) to the tip of the probe which is not insulated. Assuming the tip is at the base of the hair, you will effectively treat the hair. If it isn’t insulated, it will let out some of its frequency all the way down. The top of the folicle doesn’t need any treatment although it will get it anyway if it wasn’t insulated.
-Before doing the treatment what is the best thing, wax? shave? and then wait to treat them in the regrowing period.
Don’t wax. It can and will distort the folicle over time and will make it so you will have to use the blend method to effectively treat the hair. I suggest shaving 2 to 5 days prior to your treatment. This will make it so you are only treating hairs in their androgen phase.
-If I’m using for example a Sterex thermolysis how much time do I push the needle holder button? Just a moment?
Can’t help you there. I assume that you are using the Sterex brand epilator that is not marketed or sold commercially in the US. If it does flash 1/100 of a second or less which you couldn’t do with your finger so I assume it doesn’t. If it is slow thermolysis, it would be between 3 and 8 seconds per hair. Treat the same size or thickness of hair once you have determined what you want to do. It will vary depending on thickness. Start with the shorter amount of time. Slightly pull on the hair and see if it will easily slide out. If not go on to another. Do not keep trying on the same hair until you have figured it out or you will overtreat the folicle.