Lack of data when performing hand calculations
How does each one of you deal with this parameter or parameters, which value is not given by manufacturers?

By not obsessing over things that aren't relevant and don't lead to a better design.

The detailed parameters of transistors can vary considerably between parts of the same model, and for the same part over temperature.  Good circuits use transistors in such a way that the exact parameters don't matter, as long as they meet some minimum requirements.

For example, a transistor may be specified with a minimum guaranteed gain of 50 at the operating point you are using.  However, it's not unusual to find individual parts with much higher gain.  200 or more wouldn't be out of line.  Unless the datasheet specifies a maximum gain, and they rarely do, you should design your circuit to work as long as the transistor has a gain of 50 or more.  Fortunately, that's actually not so hard to do.

Note that at infinite gain, the base current is 0, and therefore the input impedance in common emitter mode is infinite.

If you find yourself wanting more definitive specs for a transistor than what the datasheet tells you, it's a strong clue you're not designing your circuit robustly enough.  Go back and think up a better topology where you don't need to know these things.