Ah, yes. It is a little embarrassing that we don't have that map, but once Chrono Cross's location map assembly is deduced, outputting PNGs of every map in the game will be a piece of cake.
1. It's unavoidable; we have to examine things from Belthasar's perspective. In shattering, the Dragon Tears provided the multidimensional pieces used to make the Chrono Cross, and they were only meant to shatter in 1020 A.D. So, A) they may always shatter after use, and just were never used in El Nido's history, or B) Belthasar arranged for them to shatter in those particular uses, supported by the possibility that Lynx wasn't doing the ceremony according to correct Dragonian ritual. That possibility is debatable, since Lynx was with FATE, and FATE controlled the Dragonians and would know all the rituals they performed. So I guess there's always the chance the Dragon Tear was created back in the Reptite Dimension, too. It's inconclusive.
2. At that point in the game, the player would not know it's not the Frozen Flame. I mean, the player knows anyway because it's a New Game +, but I think the ending just assumes Lynx really does have the Frozen Flame, and goes from there. It's like the other humorous endings, or the endings from Chrono Trigger which wouldn't fit in canon (like Frog's mating with Leene).