Can someone explain?

Concerning point 4. the film has nothing to do with derelict on LV-426 the space jockey and ship are different. Theres defo more than one. As for the large face-hugger thing. Look at how large the chestburster turns into xeno in a matter of hours. Same prinicipal - mature quickly to ensure self-defence and survival. Point 6. I'd say let your imagination surmise that theyre running away from their creations etc, but leave it open for debate. Not everything needs an answer.

It's unexplainable and sad very sad.

While not necessary, it would have been nice if LV-223 had turned out to be LV-426. That is, if the Engineer had woken and in the ensuing chaos had been implanted by Shaw's Baby before firing up the Derelict, then upon crashing the Derelict, had been knocked unconscious in the Gun chair. While he is out, the Xeno is birthed and hunts down the rest of the crew on the surface of LV-223. Then in the next 30 years perhaps some cataclysmic event (meteorite?) happens to change the surface of the planet, rendering it inhospitable. The Nostromo then comes along. Etc.

For point 1. Maybe to initiate that level of dna expansion the space jockey did need to die. It seemed reasonable to believe. Plus it connects to something David says later in the film - ' sometimes in order to create you must first destroy.' Dude I get there are quite a few things that are complicated and unexplained but thats part of the fun to leave questions and create speculation (it adds to the mystery and lets your mind use its imagination). In Alien was the derelict or Space Jockey ever explained? Or the Xeno's point of origin? Nope. I get some of the things your saying I just think if you nitpick too much you overly criticise and then your opinion of the film will deplete. This is why critics have been a bit overly - critical on the reviewing.

the lifeboat gets dumped by Prometheus, then vickers ejects in an escape pod from the prometheus. she lands near shaw on the surface

Pointone: Ceremonial garbs, etc, they give life to create life. Thats what I gathered from it. Many a culture believes in life from death so maybe thats whats tried to be shown here.

1) The suicide makes one think that the Engineers had not much value for (their own) lives. This could be, because they have a different view on death then humans (maybe they also believe in/know about afterlife, or have a greater purpose like religion). But we don't know how long these Engineers live, but since the head was still able to be brought back to life, probably a very, very long time. They also show a lot of hostility towards us. The last Engineer killed the humans instead of engaging in a conversation. It was probably not a rogue, since the different caves with similar images show evidence of an operation, conducted by a group, instead of one individual. 2. this is a bit of a flaw, but we can see the life boat crashed and was not able to fly away. This could indicate that the ship crashed and by coincidence in the same area where Shaw was. Or she must have run to Shaw since one would immediately go to the other human(s). 3. Shaw running around, jumping, fighting, etc... after a C-section surgery minutes before(impossible). Shaw escapes from the sedation table, makes it to the operating pod in Vicker's lifeboat and completes the surgery with nobody chasing or looking for her? 3. Also a bit of a flaw. But whith all the adrenaline and drugs she got from the operating pod, this is possible. And I guess we have to think that the old man was about to die, and nothing really mattered, except from engaging contact with the last Engineer. So the whole situation with Shaw was temporarily unimportant and the android's goal was nothing more then the old man's goal. 4. The size issue is not clear, but remember that the small wurms also grew out to be thousand times as big as their original form. Since the alien inside Shaw was meant to be a human in it's original form, it could have grown much bigger, just like the wurms. i have to say that the alien inside Shaw reminded me of an alienized sperm cell. The SJ from [i]Alien[/i] is not the same as the one from [i]Prometheus[/i]. Why? The eggs.. The eggs show sign of a queen Xenomorph. And since the SJ's show no gender, it is likely that the queen is a result of human contact, in which the feature of reproducing ourselves was adopted by the black parasite. 5) The size change is just an effect. We saw that with the wurms. The black goo is not acidic. It is the blood of these creatures that is acid. If the black goo was acidic, it would have vaporized Charlies drink, when David put it there. 6) The point was that these holograms showed something of a big happening/accident and interfered with a very important mission. The fact that there was not seen any interference from other Engineers on LV223, since the accident happened (2000 years ago) and was left behind the same way since the accident. This could indicate that the accident happened on a big scale (for Engineers). That it was an important mission can be seen with the last Engineer, who did everything to complete his mission, and rather killed humans, instead of engaging in a dialogue. The green goo was probably a remnant of one of the Aliens that killed the Engineers. Where the Aliens went I don't know, but it could be that the Alien died in the 2000 years, the same way the Alien died on the ship from [i]Alien[/i], which is encountered by Ripley and her team.

5) Ow yeah, the black goo is something different than what was inside the yellow glass (the context of the black vase). So the black vase contained black constructing DNA (used to create humans) and black parasite DNA. The question is what would happen when combined? Maybe a Xenomorph would grow out of it (just like the image of the wall decoration)? Or a five fingered parasite?

From what I could see Vickers did not have enough time to make it to the life boat part of Prometheus, so she got into the pod instead. She then had to get out of the pod as soon as it landed on the planet and them try try and make it to the lifeboat. Not aware that the lifeboat had been damaged during its decent to the surface of LV-223.