Is the X-ALP Alpine Echoes good for hiking?

It handles light trails, gravel and packed dirt well thanks to the rubber outsole and structured upper. For long or rocky hikes, a mid-cut boot with more ankle support is the better choice.

You can, but it is not built as a running shoe. Cushioning is modest and the leather-and-mesh upper is heavier than Salomon's trail running models such as the Speedcross.

Salomon trail shoes generally run close to true to size with a fairly snug fit. If you wear thick socks or have wide feet, consider going up half a size.

No. The leather and mesh upper is breathable rather than waterproof, so it will wet through in rain or deep puddles. Salomon's GTX versions are the waterproof option.

What is the difference from the X-ALP LTR?

Both use a leather-and-mesh upper and rubber outsole in the same X-ALP shape. The Alpine Echoes is a distinct colorway of that design rather than a different build.