1a. Yes, the goals of the Boost program include finding high quality stories that might otherwise slip through the cracks.
1b. Whether a story is in a publication has no impact on whether it is selected for Boost. That said, when a story is nominated, the nominator has the opportunity to offer additional information about why the story should be Boosted. If the nominator is a trusted editor running a high quality publication, the additional information they share can educate the curation team about why the story should be Boosted. So while being in a publication has no impact on getting Boosted, being well recommended by a trusted editor of a quality publication can definitely impact a story getting Boosted.
2. Our commitment to writers is that 95% of Boosted stories get 500 additional views within 2 weeks of the story being Boosted.