With social media purchases, make sure you always ask for references when working with someone new, and trust your gut (if a deal seems too good to be true, it probably is), and you should be fine
It just produces one mana of the appropriate type, with no restrictions or riders
You get your Banishing Light effect for slightly more mana, but you also get a white mana rock to help make up the difference
Im always going to wait, Fatal Push a cost reducer if they cast one or Opt if they dont, and Thoughtseize after they spend another turn cantripping to maximize my odds of hitting a Gifts Ungiven or ruining their setup
White and/or blue are musts for color identity, with access to both colors being preferred, and the lower the mana cost of your commander, the better, as it will be easier to cast
Other than Worldspine Wurm all the best green targets fall in the pretty playable 7 CMC area