Any Biblical correlations you try to connect simply from the names, hold no water, since they are so popular. Tell me, do the names Cobb, Eames, Arthur, Ariadne, Saito, and Mal have any Biblical significance? No, they don't, and those are the names of the actual ensemble cast.
Why should Nolan name every single character after someone from the bible? There are plenty of other threads on this site that offer suggestions on what Nolan may have meant with specific names like Arthur, Eames and Saito. None of the suggestions I've read contract anything I'm saying.
You want the names to be meaningless but they aren't. Cobb's full name is Domingo Cobb. The children are both named after biblical apostles. Mal is malevolent: the temptress who seduces Cobb to build his home on the sands of the mortal world. Yusef quite literally holds the keys to the dream world. And Ariadne? When Cobb asks his father for help it is given (Matthew 7.7) in the form of a woman whose mythological name suggests her purpose is to guide him out of the maze that is the mortal world. This is exactly what happens and we even get it visually symbolized when Ariadne breaks the mirrors that trap Cobb in a series of infinite reflections/dreams.
The film uses architecture because architectural knowledge is needed to form a dream world. Obviously design experts are the most qualified to build an imaginary world. It's the only profession that would makes sense to design the dream world. Again, you are trying to pull some hidden meaning out of nothing.
There is no hidden meaning: it is all in plain sight. References to the parable of the wise and foolish builders bookend the film. The film starts on the beach with the false children building castles on the sand. It ends on a cliff with the real children building castles on the rock. Nolan repeatedly emphasizes the parable by linking the sand castles to the "real buildings" of limbo, a world where "you can spend a lifetime" and from which "you have to die to wake up". What is subtle about this?
I suppose it could be a coincidence that limbo is destroyed *twice* in a flood of water exactly as the biblical parable suggests. It could also be a coincidence that water is consistently associated with the dream worlds, and that it gets progressively more destructive the deeper they go. It could be a coincidence that Cobb sees Mal's face when he washes his face, or that it's a glass of water that sends Fischer to sleep on the plane. And it could be just a coincidence that Cobb fell into a bathtub. There are a lot of coincidences. A LOT.
Except they aren't coincidences. Inception does a lot of novel things, but its use of biblical allegory and water symbolism is actually quite staid. Water is a popular symbol for the subconscious in Western literature. Nolan is aware of this, which is why he starts his film with a shot of the ocean, and why the script tells us that limbo is built "on the shores of our subconscious". There is an underlying symbolic point to the omnipresence of water in the dream world. This is not the only thing the film is doing, but it is part of the language of the film and Nolan is far too consistent with it for you to plausibly claim it is accidental.
But even if you do want to insist that everything is a coincidence, you'll have to find a better excuse than the claim that "obvious design" is forcing Nolan to adopt these images. If the buildings of limbo aren't supposed to be bigger versions of the sandcastles on the beach, why do we see them crash into the ocean? A cement building falling apart like sand... really? Another equally nonsensical example is the way water crashes into Saito's complex from above when the opening dream collapses. This makes no sense, and is actually completely illogical. What is the water doing up there? Is there a giant water tank hidden somewhere above the fortress? There is no "obvious design" forcing Nolan to end limbo by destruction of water just like there is no "obvious design" forcing him to put Cobb's chair above a bathtub. The logic works the other way: the plot devices are necessary given the allegorical structure of the film. Cobb is sitting above the bathtub because Nolan needs an excuse to flood limbo with water.
Genesis isn't a reference to the Biblical chapter. It's the most appropriate word for Cobb to use in the sentence. AGAIN, pulling something from nothing. And "Goddamn beach"?
I shouldn't have to explain that one...
If Eames had said "God knows I could use a drink" or "Heavens what I'd do for a beach" you'd have more of a case. But all you seem to be saying is that screenwriters don't actually think about what they write. A better comeback would be finding a case of blasphemy in the film that does NOT work with the interpretation I'm giving you. But you won't because characters rarely swear and when they do it tends to be significant and meaningful.
Self sacrificial death? What the hell are you talking about? Waking up from Limbo? He has no choice but to if he wants to see his kids again and live in reality. Anyone in his position at that time would have done the exact same thing without much hesitation. Yet again, pulling something from nothing.
The film sets up being trapped in limbo as a death sentence. So we have Cobb sacrifice himself to rescue Saito from limbo. Nothing particularly deep here although it's worth noting that Cobb's clothing and behavior is quite different in this scene from when we see him earlier. He's changed from thief to prophet.