Uh, some of the regional pricing may differ between the stores, but for the most part, the game should be the same price everywhere.

Will my save files work between the Steam and the Epic version?

Yep, they totally will.

So if you happen to own Steam and Epic, they're both gonna work.

We have no intention of making the save format for each platform different.

So the only difference is your save files might be located in different places on your computer.