Unfortunately, the immediate discard requirement and potential to miss an OHKO make it too situational
Sometimes you want to cast it during your opponents turn so that you can untap and play the new things you drew, but sometimes that additional life is great
Ah well, I think that's only a limitation that matters for a short period of time, as most people aren't going to care three months after release if your flashback deck had Grizzly Fate at the same time as your populate deck had token making engines
The deck that makes the most use of Solitude is probably 4c Elementals where it can be tutored up and then Ephemerated for some crazy value , but it is also vital for Azorius Control where it represents one of the few threats the deck can present
Since its text states specifically a graveyard, it means any graveyard, yours or any of your opponents
all you need to know for Swinging Ship is you need to open the attraction, roll a 6-sided dice, and get a 2 or a 6 during your first main phase, and then you get an additional combat phase after your first one