I don't think you'll get lower than the $20 that it is now. If you really, really want it for less then you can wait till probably a big holiday sale across steam and hope Factorio is one of them lol

Probably wouldn't be detrimental to the game, but something that should be lower on a priority list I'd say. There's other issues that are more important

What about the legendary answer to life the universe and everything being 42?