As you should do.

tbh it just looks a little out of place, that could easily just be a "Horrors of Rapture" screenshot, minus the Big Daddy.

That Big Daddy (heavy weapons one) was cut out of the game so that the devs could focus on polishing the other Daddies in order to get the game out the door in time.

That's their word, not mine. The AI has some very rare glitches in it already, so I can't imagine how bad the Heavy Weapons Daddy was, as I remember the devs saying they were having a hard time designing the levels since they had to figure out how the Daddies and Little Sisters would move through the space.

And I assume the AI would be quite difficult to make for a Big Daddy, considering what they have to do - not attack you unless provoked, attack Splicers when provoked, look for Little Sisters, AI for when they're attacking something, protect Little Sisters..

...know when to just engage in combat instead of throwing the Little Sister on his back, know when to charge (in the case of Bouncers), decide when an attack is threatening or not (especially from a splicer), deal with the Enrage and Hypnotise plasmid, know how to react to scripted events, know how to pursue the player, etc.

Not in stores. You'll have to find it on an online reseller like eBay and be prepared for a hefty price tag.

That pic of the old/fake daddy made me think that maybe they would be good for DLC. Perhaps they could release some new plasmids, tonics and a new style of Big Daddy into the fray?

The only trouble I can see for new DLC like that is integrating it into the single-player. I mean, for multi-player games and releasing new maps, it's fine as people can just load up the new maps and play on them.
But if say, a new plasmid was introduced, when would it be able to be used? Would you have to start a completely new game to have it on that saved game, or would you have to buy it from the Gatherer's Garden? Tonics would have to be found, as you barely get enough Adam to buy every Tonic and complete the Tonic Collector achievement. So, you'd have to start a new game to collect the Tonic.

If they released DLC then they would at least put the effort in to make you earn it. Such as add onto the game at the end like it was an extra content feature or modify the game that would allow you to access it from a game save. In other words they wouldn't just add a tonic into the game they would give it a background. Probably give it to a big daddy as a reward or make a new map just for the tonic etc.

And to be honest I don't know for sure but I think they would make it so it could be accessed through either a game save or a new game.

Unfortunately the game isn't open ended and does have an end so I am not sure how they would approach it but then again there is evidence in the PC version that an editor exists

I missed you guys. Im back now. =D