using ITOA... Integer to Ascii... is some of the reason that's why I'm using 'Int' instead 'Byte'
You may need to learn about casting, then. Typically, a value will be implicitly cast to a larger type, but must be explicitly cast to a smaller type.
So, a byte (or uint8_t) will be implicitly cast to an int for itoa() to use, but you might need to explicitly cast the int returned by atoi() to a byte (or uint8_t).
How much I'll improving RAM on each 'uint8_t' instead 'Int' ?
50%. A uint8_t is one byte. An int is two bytes.