Verified answer

One, individual photon of light will not lose energy over any distance, however a beam of light can lose energy, if individual photons are deflected in different directions by dust, gas molecules, etc., or if photons are absorbed by some substance.

The light does not lose energy as measured in the frame of reference it is emitted in, even after traveling 10 bly's. It appear red in our frame of reference because the universe is expanding, so we are receding rapidly from such a source. This causes the light to be Doppler shifted, just as a receding race car appears to be emitting a lower frequency of sound than heard by the driver.

Redshift does not happen because of distance, it happens because of relative velocity. It happens that because of approximately uniform expansion of the universe, further galaxies are also moving away at a higher speed.

If there were an observer just outside the distant galaxy, but moving at zero velocity relative to our galaxy, they would already see the light reddened there. It would get no redder as it moved from them to our galaxy.

No, it does not. But it does diffuse: the beams of light tend to spread out from their origin, so a point far away will only receive a little bit of the light.

no, there's no evidence to suggest that light can lose energy