In order to play, you'd need an updated damage deck - best way to get that is from the new core set. It'll also contain the updated shield and new Force and energy tokens. Those can also be found in the conversion kits, though I wish they included more (especially shields). If you've got the conversion kit, you won't need to buy the second edition ship expansion (i.e., you won't get anything new in the 2.0 X-Wing expansion that you wouldn't also get in the Rebel Conversion Kit, except the new poseable X-Wing mini, of course).