What is the unit of a value returned by myjet.pt()? Is it GeV? And do we need to check if particles satisfy

A transverse momentum is always expressed in GeV... for particle physicists. The trick is that in our system of units, the Planck constant equals 1, and the speed of light equals 1. With this in mind, everything is much simpler :)

For the 'loose' stuff, please ignore it. Electrons can sometimes be confused with jets, as I said in the post. Therefore, you impose different identification criteria to determine whether an electron-like object is really a electron or is in fact a jet. There are many of these things we cannot handle with public tools. So that we make approximations. For now, just ignore it. In the next post, I will start addressing the part we can cope with.

I also assume that transverse impact parameter can be ignored as not mentioned in your post.

Exactly! For anything :)