1. Well, the quote from the manga says: "The fact that you consider that Sakura over there most precious, doesn't come from my heart. It's from you!" ..or something along those lines. So yeah, basically I believe Cloney loves the cloned Sakura, whilst R!Syaoran loves R!Sakura and vice versa. Exactly how the reals can love each other is unclear, but that's the implication. In my opinion, I think it's perfectly plausible that R!Sakura fell in love with R!Syaoran's heart that resided in the clone during their childhood years, but it could just be that R!Syaoran was actually in Clow Country before the clone's appearance and R!Sakura's memories were wiped or something of the sort. It's a mysterrry~
2. Nobody knows. D| *glares at CLAMP*
3. Possibly. It might just be a different Clow Reed that Syaoran was descended from, though... In fact, it probably is.
...Regardless, Sakura and Syaoran were actually related in CCS, aswell - Sakura's father, Fujitaka, was Clow Reed's half-reincarnation, whilst Syaoran was Clow's descendant.