Reverse engineering, doubt with value of capacitor
1) Are they ceramic capacitors?


The capacitors in the photo of the link appear to be 0603 ceramic capcitors.


  2) is correct the procedure of unsolder and measure? 


Yes, usually the best way is to unsolder because the other parts of the circuit are in parallel with the capacitor. By taking it off the rest of the circuit is not measured. I do this all the time (especially when I forgot to write down what I put on my PCB)


  3) Is there another procedure to do it?


An RLC meter (or tweezers) can be useful. It's most useful if you don't wish to pull the parts off the board, they can get withing 10% most of the time so if you have an idea of what the capacitance could be they are a great way to check. 

It may be better to get one or more boards and repeat the measurement and average the capacitor values together because of capacitance tolerances.