Obi Wan: flip this card to remove a stress, tractor or ion token. Flipped side FORCE GHOST Obi Wan once per round any friendly ship may spend a focus token to reroll any number of attack dice instead of its usual effect.
Yoda: you may, or may not. There is no try.
Turning a card over means you're discarding it, as per the rules.
Not if it's double sided (maybe) we don't know what Dual Upgrades might be able to do yet.
But in that case, 'discard this card and replace it with FORCE GHOST Obi Wan for the remainder of the game' would work instead, and give the force ghost the cost '*' indicating that it can't be paid for with squad points.
Do we know that dual upgrades are double sided? And even more so (and this would make sense given the emails about R2-D6 and Integrated Astromechs): currently you can't discard your EPT.
You can lose crewmembers though or other upgrades though, and discarding is now done by flipping the card over.
We don't know for absolutely certain, but given that we've seen two different sorts of art for Adaptability, and two different effects, and only one of the sets of artwork is visible on both copies in Mist Hunter, it seems likely that they will be doubel sided with the other artwork (and effect) on both sides.
But we have 0 idea of how the rules for them will work as yet.