It wouldn't be hard to explain how the squadmates got on the Normandy before the extended cut. I would like for Bioware to explain how Steve gets back on the Normandy
It seems that it confused enough people that they ended up having to clarify it in EC. Of course, if you're creative enough, you can explain almost anything. As for Steve, no idea. My memory sucks, but I'm not even sure where he is at the time he calls Shepard in the FOB. But, well, there are plenty of things I have no idea about. Like, what's the whole crew doing while Shepard's getting her butt fried out there.
As mikefest said, its called a Hades cannon. Wiki entry.
Ok the destroyer entry lists the Hades Cannon under destroyers destroyed by Shepard.
Well I assumed it´s something else that only shares a similar movement system . Just because my car has wheels doesn´t mean that it can take the same damage as a wheeled APC. Something like that. I just assumed that it´s not supposed to be a full blown Reaper because it would just be too silly, after you needed a whole fleet on Rannoch and ehm two Thanix missiles on Earth. If A Cain would be enough this group suicide attacking the destroyer would have actually won. 
Ah well could be that it´s an actual destroyer. Dunno, perhaps Duty as a Hades (Glass) Cannon is a disciplinary measure handed out to Reapers who displeased Harbinger or so. Turns you into a really fragile, big target.
Yeah, I know what it's called. I was rather wondering what type of enemy it is and how tough it would be to kill. I did assume it was something destroyer related because it just looks similar, just with the cannon on the top of it and it doesn't seem to shoot the regular beam.
But that's my point all along, lol. Suddenly, we can take down Reapers, apparently, with a Cain. WHY DIDN'T WE TRY IT BEFORE? WHY DIDN'T WE DO IT AFTERWARDS? Whether it would work or not, we can only guess because the game doesn't tell us or show us. As for needing the whole fleet, it's hard to say whether it really is necessary. I think that's simply what we had at our disposal at the time and then BW decided to have a boss battle. And, well, we took down one Reaper using a thresher maw, too. That thing doesn't even have the option to make stuff explode. It just crushed the bastard like it was nothing. I guess there are more ways to kill a Reaper. I mean, I know a whole fleet synchronised seems like a big deal, but Cain is a mini-nuke. If one hit didn't take a destroyer down, maybe two would. Hard to know like this.
As for the suicide squad, one of the guys there does have a heavy weapon, but from how it works, I think it's rather a grenade launcher and not a Cain. The explosion was rather unimpressive.
Thanix missiles are also amazing. Since when do we even have Thanix missiles? Thanix cannon doesn't shoot missiles. I didn't know what was a thing.
I thought the idea of getting either the Reaper heart or mind depending on which choice you made at the Collector Base was pretty cool at the beginning, but now I think it would've made most sense to only get those when you have really low EMS. So that either Control or Destroy can come from this decision. In high EMS, you get both anyway, so that choice doesn't really matter then. Or to not get the mind/heart at all. I wouldn't really miss it, haha.
But I'm not sure this all happens during a "few hours". The game has to move forward quickly because otherwise it would be very boring, so I always assumed all of this doesn't happen within a short amount of time.
And actually, yeah, the Crucible team seems to be badass 
Completing the Crucible device will require entire systems of resources and skilled workers, as well as the galaxy's brightest scientists.
It's a Destroyer class, but anti-aircraft, so it's a bit different than the Reaper on Rannoch.
Yeah, it's hard to say, but the game makes a big point about it being a huge rush and, generally, using the mass relays and FTL travel makes distances shorter. I think that salvaging such a thing (That also means they'd have to stay at the base for a while.) and then trying to find out what it does and then also installing it into what's basically a finished product... well, I'd assume it would take a few days at least, even if you have the rachni aboard. Otherwise, I agree that the game makes everything look like it happens during a short time when it, in fact, likely takes months.
Indeed, it works and looks different, but we know next to nothing about how much beating it can take. I mean, the cannon and the tubes on its legs aside, it looks identical to a destroyer. Is there a reason it should have been made weaker? That's where my assumption that it might work on the other destroyer comes from. It doesn't even look different in size to me. I mean, sure, I can very easily be wrong, but we don't really get a chance to find out.
Lol, I don't doubt that the Crucible team has only the best. We hand-picked them, personally, after all. 