GTA V (PC) Delay and General BioShock: Infinite Confusion

For the last few weeks I've been anxiously awaiting news about the upcoming release of Grand Theft Auto V for PC.  It was slated to be released on PC on January 27th, but according to news yesterday the release has been pushed back until March.  This is disappointing, but not surprising.  I thought it was weird that the Steam page for the game wasn't allowing pre-orders.  Oh well, we've waited for  years, what's a few more months?

I am continuing my second playthrough of BioShock:  Infinite in an effort to not only find things that I missed the first time, but to also gain a better understanding of the game.  Overall I have paid much closer attention to my surroundings and some things are making slightly more sense but I still have many questions.  I am also refusing to look up theories and explanations in an effort to puzzle it out on my own.  Knowing my usual weak will when it comes to looking up information like this I have a feeling I will cave and look up many of the answers I seek.  Here are a few that have been in the back of my mind as I've navigated Booker and Elizabeth through Columbia.  Some of them are new discoveries from my most recent playthrough and some are lingering questions.  (Possible spoilers ahead!)

1.) Is Songbird a different version of a Big Daddy?
In this playthrough I have listened much more closely to the many voxophones that I have picked up.  It becomes obvious from listening to many of them that Fink and his brother are taking advantage of the many tears in Columbia.  Fink's brother Albert is stealing music from the future and selling it in the past.  In one of the voxophones Fink mentions that he has seen a Big Daddy and that it would be useful to guard Elizabeth in the tower.  For some reason I didn't catch onto this fact during my first playthrough.  Other things should have stood out--the changing colors of Songbird's eyes, much like the colors of a Big Daddy as you approach it.  Songbird and Elizabeth also seem to have a strong bond similar to that of the little sisters and Big Daddies in Rapture.  But then what does that make Elizabeth?  The original little sister minus all the weird Adam sucking from BioShock?

By coeykuhn.  Nice interpretation of the twins.

2.) Are the Lutece twins the same person?
I do not understand the Lutece twins and the general quantum physic idea of them being able to alter space and time.  In another voxophone it is suggested that Rosalind Lutece was an only child and it was never recorded that she had a brother.  Later you find another voxophone where she mentions that she has gone to a different universe and found her brother "all that separates us is a chromosome."  So in that universe did she have a brother or was she actually born male?  I really like the Lutece twins as characters--they're quirky and fun but I don't understand their relationship.

3.) How are the Lutece twins able to be in all worlds?
In another voxophone clue it is revealed that the Lutece twins were killed by Comstock in an effort to cover up the origins of Elizabeth.  Their device for travelling between worlds was tampered with (also by Comstock?) and they were dispersed to all worlds but are dead in the original world.  I think, anyway.  Ugh--all this quantum physic-y stuff is creating some cognitive dissonance.

My brain hurts from trying to figure out BioShock:  Infinite.