First part - No idea, but Funkfreed is a sword with the elephant Zoan, so we know it's possible for swords to absorb fruits. I think it's something to do with the whole "fruits have their own will" thing, but that only applies to Zoans, and Issho's fruit is a Paramecia, so I'm not too sure if his sword actually ate the fruit but it's still possible.
But then again the only weapons we saw with a fruit were Zoans.
Second part - Probably, after all he knew how to steal Whitebeard's fruit right after his death.