There aren't any further ways to get the Apricorn balls, regrrettably. They're really good to use, but it feels like such a tease. This site's Itemdex also shows where you can find Samson, though I don't think there is any list of them all in one place. Not all of them are derived from Samson though.
From what I can put together, the following are obtained through finding Samson:
Friend Ball - Malie City (first encounter)
Love Ball - Malie City (after seeing him in the other locations)
Lure Ball - Blush Mountain
Moon Ball - Mount Hokulani
The following are just available out in the open:
Fast Ball - Mount Hokulani
Heavy Ball - Mount Hokulani
Level Ball - Mount Hokulani
What I use to verify Hidden Abilities varies on a case-by-case basis. You're looking for Impostor Ditto, an ability that should activate as soon as Ditto enters the battle, which means you don't need anything special. Whenever I can, I'll look for a way to induce an automatic trigger. For instance, when looking for Contrary Fomantis, I raised a Surskit to have Sticky Web, then deployed it at the start. Each time a Fomantis appeared, I'd watch carefully and wait for the one whose Speed rose instead of fell. For Anticipation Eevee, I simply kept in a Pokémon with a Fighting-type attack and looked for the one that shuddered when it appeared. For Sniper Fearow, I watched the damage my Absol with False Swipe sustained and looked for the ones that did damage out of proportion to their normal critical hits. (It helps that most wild Fearow know Focus Energy.) For Gooey Goomy, I attacked each one with False Swipe as they appeared and looked to see if my Pokémon's Speed decreased.
For cases that cannot be verified through in-battle effects, I have a Kadabra with Role Play. I learned the hard way NOT to evolve it into Alakazam, as Alakazam learns Calm Mind instead. Role Play has 20 PP as opposed to Skill Swap's 10, though it's not that much when you often have to chain well past 20. For that, I have a huge supply of Leppa Berries.
By the way, Alolan Sandshrew's Hidden Ability is Slush Rush, is this correct? If so, one way to verify it automatically is to catch a bunch of Alolan Sandshrew and determine what the range is in their Speed stat. Then, bring in a Pokémon with Hail or Snow Warning whose Speed is more than that but not twice as much. (And a lot of healing items and PP-restoring items.) Since wild Sandshrew have no priority attacks or Speed-modifying moves, you look for the one that outruns your Pokémon when it's hailing.
The QR reader for Pokémon Sun and Moon makes use of the 3DS's bottom-quality camera without allowing you to change the exposure or white balance. The QR codes will not scan unless the room is very brightly lit (meaning I cannot scan these at night under artificial light), and for some reason, it cannot read QR codes from my monitor or tablet unless the contrast is turned up to its maximum.
In fact, my first QR code was on my computer--I had to print it out and stick the paper under direct sunlight of an open window to get it to scan.
In this situation, you would receive 4 points in Special Defense and 32 points in...Speed, or whatever stat Power Weight increases.
Celesteela is RIDICULOUSLY hard to trade for though. Every time I see one where they ask for Kartana or Buzzwole or some other Sun-exclusive Ultra Beast, someone else has snatched it before me. No other Pokémon I've seen has demand this insane.
