About that 2nd Lerasium bead, I don't ever remember a 2nd bead being mentioned anywhere I can think of, however I think I might know what Chaos is referring to about the speculation. When Preservation pointed the bead out to Vin she origanally thought she was supposed to burn it, He stopped her from doing so and instead got the point across that she was supposed to give it to Elend, Brandon did say however that if Vin were to have burned Lerasium, because she was already Mistborn there would have been interesting results.
If there WAS a 2nd Lerasium bead (which there very well could have been) then it is entirely possible that Hoid has it, it was the alternate ending he posted to WoA on his site that he said had some intresting clues about Adonalsium, in that ending Vin sees a trail of footprints leading to the Well that I'm 99% positive were confirmed to have been left by Hoid. what would have Hoid been looking for in there, he obviously didn't do anything with the Well, and if there was a second Learsium bead then that could have been what he needed.