Yup. Very difficult. I’ve studied this stuff extensively. The arguments against the possibility of FTL are just plain wrong. They talk about paradoxes and such. FTL that causes paradoxes is not possible. FTL that does not cause paradoxes is just fine.
Nothing with mass can move at the speed of light. But space itself can and in fact provably does between some galaxies.
You’re right about the energy requirements. Only possible source to get there is antimatter, which is insanely expensive. But it wasn’t that long ago when getting a plane to go 100 feet was a huge accomplishment.
Yes, space expands faster than light at about 14 billion light years distance (the universe’s visible horizon). It’s notoriously difficult to predict the future, but I would guess it’s not what we expect.
I do love when people take (current) science-fiction & current Human understanding (given we haven’t even set foot on Mars, let alone outside our own star system, “But, but our MODELS...”) & speak in absolutes