The discovery mod seems to be quite a recommendation, but it's available in versions 4.85, 4.84 and 4.83 and each readme states a different year in which the new story takes place, and in 4.85 openSP is no longer optional but enforced. I'd like to play the game once again from the very beginning including the story but wouldn't mind testing the discovery improvements directly at the start, so should I use 4.84 or play the story first and then use 4.85? Or is the intention of the mod to start a new game as "Trent jr" anyway?
4.85 OpenSP enables once you complete the storyline.
Normally once you finish FL on an unmodified version, once you start the final mission set you get your final level boost (Cash value + asset value) calculated as per multiplayer and then the game 'locks'. You are no longer able to level, there are no more story missions. This means you can be stuck at level 17~ which is below the level 23 for the top level gunship. Open SP lets you continue on afterwards so you can buy the top Rheinland ship.