Tell me please, how can I directly get a note from a .mid file, note duration and time when it should be pressed on the keyboard of a synthesizer? How to find this data in hex code?
Use DAW (digital audio workstation) software or a MIDI sequencer to read the file and present the details to you in a Human friendly way.
If you want to learn what the bytes in a MIDI file mean, you can read the Standard MIDI Files specification available in the "Specs" section of www.midi.org. If you get to a part of the specification that is confusing, you can ask a question about it here on the forum and someone may be able to help explain it.
If you think the specification will take too long to learn, you can explain more about what you are trying to do, and someone may be able to suggest an easier method.