Electron repulsion is irrelevant compared to the energies needed for fusion. It only takes a few eV to throw electrons out orbit, since they are so far away from the nucleus. On the other hand, a nucleus itself would be attracted to these electrons equally much approaching them and passing them, resulting in a net 0 effect.

The electrostatic effect of the 2 positive nuclei repelling is WAY larger due to the extremely small distances needed for fusion.

Do you mean the other way around? German companies had the patents for synthetic rubber, most notably Buna-N, and when the USA joined they simply stole it?

The electron pressure is always there.

But you are right regarding the thermal energy making fusions easier, which can happen at any pressure or density with enough velocity. At this point I am not even sure which of the 2 approaches (cold and far denser or hot and far less dense) would be “easier”, where we would have to first define what easier would actually be…

Heat means more vibrations, which means less density and more force needed to compress the matter to the same density. Just compare any solid material to plasma. Or the 100 million kelvin plasma at ITER, which has an absurdly low density (like a high vacuum) but still 1 bar of pressure due to the thermal pressure.

Electron degeneracy pressure is always present when there are electrons, regardless if they are part of an atom or free moving in a plasma.

Why? What for?

Wouldn’t the hot part actually make it harder…? All you want is density and as little to counter gravity as possible.