Now, this is interesting. I didn't get this impression at all; where did you find the clues that suggested this?
I don't understand why Bethesda tried so hard to convince us that the game gives you the freedom to make your own character. Tired criticisms aside, the story is clearly tailored for us to care about our character from an outside perspective; their idyllic pre-war life is meant to show us how much they've lost and how disorientated they would be by the post-war world; this leads into their obsessive search for the only thing they have left in this world (Shaun) and gives us an opportunity to sympathize once they become utterly broken by the discovery that their son was their enemy all along.
Now, of course, this isn't the most original of stories (and even then it is done rather poorly), but it would have benefited greatly from a character with a defined personality we could grow attached to, which Bethesda seemed to have been planning but only went half-way with it.
Well, unfortunately, I did buy into the hype and bought Fallout 4, long before I discovered NMA. Back before I got disappointed by the severe lack of actual, written quests, I did a lot of exploration. I preferred to explore urban decay rather than the outlands of the map in south, and ran across several military checkpoints which had entries regarding issues with foreigners, underground ration storage running low on resources, and of course, police stations littered with reports of criminals all over the place.
Now, the criminals aspect is a bit of a stretch, but Bethesda clearly implies that pre-war Boston was not a paradise. You are even given an option to say to a pre-war ghoul that the world before wasn't all that great as people thought it was. It definitely was intentional, trying to create the feel that the world before the war was not in good shape. Bethesda aren't masters of storytelling, to say the least, but they
did have a vague idea of what Fallout pre-war was supposed to be - not wacky techno 50s fun times.
So to me, the entire introduction sequence is not only poorly-paced and loaded with cringeworthy dialogue, but it does not fit in with literally any lore Bethesda tries to present during the main game. I know they were trying to explore themes of loss and detachment, but it feels almost like whoever wrote the intro and whoever wrote the rest of the game never met during the entire development of the game. I believe that the writer for Bethesda that did background writing and adding little bits of information to fill the gaps is the one who should have been the lead writer.
Possibly; mongrels usually hunt in packs, so it's entirely possible that he was killed by the rest of them (though the lack of missing flesh suggests he was either not very tasty, a clothed corpse is difficult to model or I'm just plain wrong). Personally, I think this particular man is one of Bethesda's few instances actually deserving of their fame for visual storytelling.
I find it hard to believe that a veteran would be allowed to keep such a valuable piece of technology, considering that the fact that there's more Power Armours than Power Armour stations makes them too valuable to do so. Your suggestion that it might have been used by the soldiers guarding Vault 111 seems reasonable, but as you said, it didn't appear in the intro and Boston was nuked basically seconds after that, so they'd have to have decided to modify or repair their PA by dragging this station from wherever they were hiding it after surviving a blast that either killed or ghoulified everyone else.
On a side note, the fact that these T-60s had already been deployed but are still somehow rarer than the X-01 (despite it being a post-war design and there being two factions that wear the T-60 almost exclusively) is just another example of Bethesda congratulating themselves by making their design the special one.
Bethesda's visual storytelling tends to be very artistic but they don't make very much sense. The kind of visual storytelling that would be much better suited to an atmospheric horror game, to build the tense atmosphere and provide insight at the same time.
I believe that the power armour frames may have been modified from the rigs used to hold car engines, which is why they can also be found at several Red Rocket stations. This might've been the case - it was built for engine maintenance, disassembled and left in the house. Though in that case, we come back to the elephant in the room of plot holes - Bethesda's insistence that nearly everything from before the war can last 200 years without falling into a state of disrepair.
Yes, the T-60 series are never explained. Their origins, their designation, their abundance in the Brotherhood and rarity outside the Brotherhood, and their similarities to the T-45. My headcanon is that the T-60 was simply a redesignated version of a later T-40 power armour, most likely a T-49. It would better explain why the T-60, despite coming after the T-50 series, bear more of a resemblance to the T-40 series. There's also the case that for every 10 T series of power armour, the US government signs on a new contractor for the next one, and the military contractor that designed the T-40 series was hired again for the T-60 series.
I know it's probably the case that Bethesda didn't give any of the above any thought at all whatsoever, but many of their plot holes were left vague enough to be filled in with the player's own interpretation, a disingenuous method of storytelling that's popular with Bethesda games. My main gripe is with the inconsistencies that couldn't be explained. Vertibird abundance for one thing.