Since it's a blank piece of paper there has to be some sort of trick to it, even though I don't want to use the word magic. But it's possible that letters will appear. Or an arrow that'll always point towards Ace's location.
I don't know
But if, as you say that paper is a message to WB why wouldn't have ace given it to WB instead of Ruffy.
When he set out on his journey, he didn't even know if he would meet Ruffy.
Logically it would be better to give it WB or some crewmember, or just tell WB to care for Ruffy.
Besides, the paper was pretty small. Whats supposed to be on it "dear Ruffy, give this to WB" and then a letter? I doubt it.
But wo knows, maybe we'll find out in the next few chapters.
There is no way Ace beat BB.
Not if you have read the same chapter than me. And look at the last pic where you can see the attacks in the distance.
The darkness attack was bigger and that suggests that it won.
Also BB was pretty much build up to be very strong and some final villain for Ruffy.
Oda wouldn't have introduced and build him up that way if he was just supposed to be someone Ace beats.
"For Feanor was made the mightiest in all parts of body and mind, in valour, in endurance, in beauty, in understanding, in skill, in strength and subtlety alike, of all the Children of Illuvatar, and a bright flame was in him"