On the blu-ray release, there are several deleted scenes that were cut from the film. There are also several "shorts", including: 1) Alien: Covenant - Meet Walter (2017) (which depicts the creation of Covenant's android crewmember, made in the style of a Weyland-Yutani TV commercial). 2) Alien: Covenant - Phobos (2017) (which depicts the Covenant crew undergoing psychological testing prior to their voyage). 3) Alien: Covenant - Prologue: Last Supper (2017) (a 5-minute scene aboard the Covenant depicting the crew - including Captain Branson - as they have their final meal before they enter hypersleep). 4) Alien: Covenant - Prologue: The Crossing (2017) (which depicts what happened with Shaw and David en route to the Engineers' planet after the end of Prometheus (2012)). 5) Alien: Covenant - Advent (2017) (which depicts David's experiments with the black liquid, the ultimate fate of Shaw, and David's plans for the Covenant crew and passengers).

Not knowing where it is is easy enough, he could just tell the ship to go home/ select it from given options. He also doesn't know what the ship is capable of so since he doesn't know where he's going or how fast it can get there he can't know how long it would take.

The crew were trying to home in on the signal they detected which was coming from a mountainous region on the planet. Faris, who is piloting the lander craft, commented that the terrain was problematic to land safely but the scanners detected a body of "smooth water" in the area which suggested a shallow depth on a relatively flat stretch of land and that she was going to land the craft in "amphibious mode. This would likely be the closest they could land to the source of the signal, which is still 8km away but at a much higher elevation in the mountains. Once they land, the water appears to only be about a foot deep. Later in the film, the water around the craft has disappeared which suggests it was either a tidal pool or caused by rainfall which then drained away (there are several waterfalls in the area which implies the latter).

Yes, this film is the second installment in a planned trilogy of movies that act as prequels to Alien (1979). It is a sequel to Prometheus (2012), taking place 11 years after the events of that film, in the year 2104. The third installment in this prequel series has no official title or release date and has yet to go into production.

In early 2015, when it was unclear whether the proposed sequel to Prometheus would be green-lit, writer/director Neill Blomkamp posted some concept artwork he had drawn for a proposed Alien sequel. Actress Sigourney Weaver, showed an interest in Blomkamp's idea and was willing to reprise the role of Ripley. Despite denying that he intended to "undo" the events of Alien³ (1992) and Alien Resurrection (1997), details of Blomkamp's film remained sketchy but it appeared to be an alternative sequel to Aliens (1986), which establishes a different timeline and basically ignores the events of the third and fourth movies in the series. The film was green-lit by 20th Century Fox shortly thereafter, with Ridley Scott producing. However, at the end of 2015, it was announced that the studio had decided to develop Ridley Scott's Prometheus sequel Alien: Covenant (2017) first. Blomkamp was asked to alter his screenplay so as to not clash with Scott's storyline. Blomkamp's project was then put on hold indefinitely while Scott was working on Alien: Covenant and its intended sequel. In 2016, Blomkamp announced that the chances of his film ever being made were now slim and that he intended to move on to other projects. In 2017, Scott also stated that it was doubtful Blomkamp's film would ever be made as there had never even been a script written for it, but simply a basic, undeveloped concept built around Blomkamp's artwork.

As made more clear in the prologue Alien: Covenant - Prologue: Last Supper (2017), many of the crewmembers were couples. Janet Daniels (Katherine Waterston) was married to the ship's first captain Jake Branson (James Franco), though he perishes in the film's opening scenes thus making her his widow. Captain Chris Oram (Billy Crudup) was married to Karine (Carmen Ejogo). Tennessee (Danny McBride) was married to Maggie Faris (Amy Seimetz). Ricks (Jussie Smollett) was married to Upworth (Callie Hernandez). Carl Lope (Demián Bichir) was married to Hallett (Nathaniel Dean).

In both Prometheus (2012) and Alien (1979), it is shown that the space crews have scanners that can detect what is in a planet's atmosphere. So these scans would indicate the air quality and also pick up on any toxins or airborne pathogens. The reason the scanners didn't pick up the alien pathogen was because it had laid dormant for roughly ten years in the form of spores. It wasn't until these spores were disturbed by the crew that the pathogen was again activated. While it would likely be wise to wear helmets on a planet you know nothing about, it's likely they didn't want to bother with the cumbersome spacesuits on an earth-like planet when they didn't think it was necessary.

While this isn't definitive, it appears that no, the planet the Covenant visits is not the Engineer home world. If one looks closely during the flashback scene; the creatures we see do look similar to the Engineers, large, with bald heads. However, the inhabitants of Planet 4 (viewed here) still look quite different from the Engineers we saw in Prometheus (viewed here). Also, the planet seems primitive and completely devoid of technology, except for the docking bay for the Engineer ship hovering above the city. We know that the Engineers are clearly technologically advanced. It's most likely that Planet 4 was another "seed planet" for the Engineers, like Earth was. If one notices during the flashback, when David arrives in the Engineer ship, all of the inhabitants of the city flock to the center of the city and cheer at the arrival of the ship. As if rejoicing at the return of their gods.