I don't think passive trainer is going to work. It never did in EvE; it just has too much meta game going for new players to quickly and easily digest. The same applies for Dust; as OP has already noted, between Core Mechanics, Core Skills, Roles and Specialisations the new player has a vast amount of options to consider and resolve before they've even stepped into a suit and deployed. It is the great strength and the keening weakness of Dust. It's depth of options and the playstyles they afford to the player suffocate before they liberate.

Anyway, waxing lyrical aside, my point is that whatever the NPE is, it's got to be fully interactive. A game mode in of itself, that provides the new player a consequence-free place so that can try anything, anytime, and learn from what works and what does not *whilst playing the game*.

A VR simulator, I suppose. My initial thoughts would be to use a small skirmish map and place an urban-type socket at its center, and have it filled with automated defense turrets such as we have now that have been hacked by...I don't know, drone? Rogue Blaster Turrets, beady-eyed sniper rail positions and such like. However, in being hacked the turrets have been structurally compromised to the point where all weapon types, and not just AV types, can damage and eventually destroy them.

New players must use cover to shelter from incoming fire, use the TACNET to understand where the enemy is positioned and move to the right position to attack accordingly, and then use what they think is the right weapon loadouts to eliminate the turrets. Do they mix damage types for efficient defense stripping? Do they attack with AV and learn of there ammo limitations? Do they try to pull out a forge heavy and go toe-to-toe with rail installations from extreme range?

Of course, all trivial to a vet to accomplish. But for a newbro, intensely valuable information can be learned, and they get to blow sh*t up as they go, which is always a bonus.