I know it says in Shulchan Aruch that, in a case where both spouses are getting married for the second time, all sheva brachos are recited under the chuppah and then after the meal on the first day only. However I've heard that a second marriage has "3 days of simcha (joy)". During this three-day period, I've heard, the bracha of "asher bara" (the last of the sheva brachos) may be said. Is this true? What is the source for this? Must there be panim chadoshos (people present who are new to the celebration) in such a case, as there must be for sheva brachos for seven days after a first marriage? What about if it's Shabbos, when we normally don't need panim chadoshos for sheva brachos for a first marriage: is the same true for saying "asher bara" for a second marriage?
A separate question, what other significance is there for the 3 days of simcha for a second marriage?