Quantum hybridized orbitals

Hello,

I have a few questions about these images that I shared.

1) What does t represent? I am assuming Es is the energy of the atoms before they hybridize, and that t is either the gain or reduction of energy due to the new orbitals that are formed through bonding. Am I way off on this?
2) How does hybridization save energy? I am not seeing why the hybridized energy when there are two atoms is 2Es-2t...It seems that the hybridization can cause the energy to increase or decrease.

I apologize if my questions aren't clear but any insight you can give me in understanding these images would be appreciated.

1. your understanding sounds OK to me

2. note that not all orbitals are filled, so the sum of all energies after hybridization is different from the initial n*E_s (number of electrons times their initial energy); that in general depends on the number of initial electrons, it is not like it works the same way in every molecule and for every combination of atoms