I'm not sure what you mean here, but judgement is about justice, not necessarily worship.
So it wouldn't matter one jot at the Pearly Gates about whether or not I was Christian when I died?
Pedantically, no. Practically, yes.
In other words, everybody has sinned, therefore everybody is automatically bound for hell. Only those covered by Jesus's sacrifice make it into heaven. This would include Christians (excluding "nominal" or "cultural" Christians).
Now the interesting thing is that God judges everybody based on what they know. So for instance, a man in a culture isolated from all outside contact, who nevertheless seeks earnestly after God, based on the natural law written on everybody's hearts, would be an excellent candidate for being covered. The same goes true for anybody who lived before the time of Christ.
On the other hand, if that same man was visited by a missionary and clearly told about Christianity, yet deliberately hardened his heart against it, he would most likely lose his candidacy. This is because his knowledge of God increased but his faith did not increase accordingly.
I think faith is the deciding factor. "Without faith it is impossible to please God" (Hebrews 11:6). You could probably make the case that worship is a facet of faith though.
Sex exists because of a 'marital bond', surely; because clearly mutual attraction is a necessity prior to consensual intercourse (note; not including prositution in this). What exactly does sex add beyond a swapping of - potentially - bodily fluids?
I mean, I'm not a fan of one night stands and I believe sex is worthless unless it's with someone you genuinely care about, but i'm not sure there's anything there which automatically ramps up a relationship 'state'. Certainly it's a bonding excercise, but also one which requires a strenghtening of a relationship beforehand.
Sex creates a physical connection by definition. It also, according to Biblical theology, creates a spiritual connection. Ideally, and usually, it creates an emotional connection, but this has no affect on the other two.
Look at the Old Testament laws regarding rape. If a man rapes a virgin, he is required to take her as a wife. On the other hand, if a man rapes somebody else's wife, he is guilty of adultery. This makes little sense unless rape is actually an act of marriage. And rape is only an act of marriage because sex is.
Incidentally, apparently some religions - well, Buddhism at least - include opinions on artificial methods of reproduction. Also, surely an omniprescent god would at least hint on these things, I mean it's not like the Bible was due to be sent back to the copywriters every century, is it?
That's like saying "surely on omniscient God would hint about stem cell research". Well, it's never mentioned in the Bible, but that's probably because it would have been irrelevant during the vast majority of human history. On the other hand, Christians can form reasonable conclusions based on established theology, exegesis, and (most importantly) prayer.
Now I'm fairly certain that no major Christian denomination prohibits assisted fertilization, for example; but again, sex is the defining marital event, not reproduction. Old Testament laws on sex do not say "if a man sires a child with..." but rather "if a man has sexual relations with...".
Why care? Is god subject to human emotions of want, now?
What do you mean, "subject to"? God is the origin of human emotions. Happiness, sadness, joy, anger, jealousy, pride, humility, love, grief, satisfaction, etc. About the only emotion that God does not have is fear.
Genocide, you mean. And it failed. D'oh.
Yeah, well, the Israelites had a terrible track record of completely following God's commands.

So they were being punished for being different. Wow, we've never seen that in history before.......
No, they were punished on God's authority, for breaking God's laws.