What type of motor I got?

[Juan]

Hello everybody!

I would like to clarify that my level of English is very poor, and to write in this forum I am using a Spanish-English translator, although I can read much better than I write...
Having said that, let me move on to the question
I have bought a mini circular table saw and I would like to regulate the saw's rotation speed (rpm).
I only have some very basic knowledge of electricity and electronics and it is not enough to dispel my doubts about the use of a voltage regulator as I am faced with a type of motor I do not know....
The only information about the motor comes from the seller who says that the motor is 220v 1200w and 10000rpm. No indication on the motor itself.
But you can see that it is a brushed motor and that it has 4 diodes (10A10 1000V 10A General Purpose Rectifier) which apparently are connected in series.
I bought a Chinese voltage regulator SRC 220v 2000w 25A, then I tested it for a few minutes on the motor with success. Although I didn't measure the speed because I don't have a tachometer.
The first question is: what type of motor is it?
Other questions:
in the case of daily use
1. Adjusting the voltage of a motor of this type can damage it?
2. Does it decrease the performance of the circular saw (e.g. torque, speed, etc.)?
3. Is the Chinese regulator I bought sufficient for the task?

Could one of you clear up the doubts that I have?

Thank you very much!