When it comes to Mr. Gaska, he is the setting writer, not the rules designer. He has vast knowledge of the lore and setting, but not necessary the same knowledge about game mechanics, Tomas have that, that is his job.
Agreed, and to be fair he said exactly that. I'm convinced now that (3) is the likely intent, though I do think it technically bumps into the "add your STRESS LEVEL dice to the roll" rule on 61, and I think that section would benefit from an example of pushing an already successful roll.
I discussed it with my players tonight after the conclusion of CotG ([Redacted] went up in a nuclear fireball, although [Redacted] was almost convinced by the remaining crew to risk [Redacted] Station), and we're in agreement that we like the tone of risking more when pushing a successful roll (even if the initial success was on a stress die), so we're going to stick with (4). Someone on FB mentioned that he thought it was "unfair" to "punish" players by having them reroll a stress die that already came up a success, but our consensus is that it feels less "Alien" if you can decide to push a skill roll based on whether your success was on (or even successes were on) a stress die. So we're going with always adding your current STRESS LEVEL to all rolls, including pushed rolls. Initial successes from stress dice just get "flipped" to base dice.
As an aside, I do think the system could use a type of Attribute or Skill roll that doesn't add stress dice. We occasionally ran into questions like, "I'm a pilot ... would I know this weird corollary to the physics regarding angular momentum?" While many time I was comfortable with saying , "You would definitely know that," or less frequently, "No, that's a little too esoteric for you to know," sometimes it was a much harder call, so I'd ask for something like a Wits+Piloting roll. This wasn't actively doing something on the spot, but rather just a test of knowledge the PC had picked up in the past, so I didn't really feel like there should be stress dice added.
Is there another mechanic somewhere that better suits these situations? Or is "Because MU/TH/UR said so" always supposed to be good enough? I'm fairly comfortable with the method I settled on, but I was surprised how frequently this sort of thing came up over the three sessions we've played. I'm a strongly "the dice fall as the fall" type of GM, so all-fiat-all-the-time makes me a little uncomfortable.