While IMO we can't draw any serious conclusions from the limited data there is, it does appear that the main reason the SR1 was hit and the SR2 wasn't was piloting error, not upgraded performance, so I tentatively concede the point.
Yeah there isn't really much on this issue one way or another, but the Codex entry says that because the SR2 is twice the siz, it needed an even larger drive core to compensate. There's a comment from Joker about how he needs to trim up the drive output and then "it will be like we never lost her", which seems to imply identical handling (within reason, anyway). On the other side of the fence we have the info (forget which codex entry its from, might be the Kodiak shuttle or SR2 entry?) about how the SR2 being larger means that it can no-longer land on all of the planets like SR1 could, so it has to use the shuttle to cover the planets that it can't enter (high grav worlds I think). But yeah, it's not really strong evidence either way.
it seems that you're talking about The Geth, since you don't mention the Reapers at all.
I didn't think it was very necessary since Collector = Geth = Reapers, they're all on the same team. Or more accurately they are all slave races of the Reapers. The geth making an observation and "wising up" means that the Reapers and presumably collectors have that information too. As I said, this means they had to have been in contact, although it's possible that the Collectors or Reapers made this deduction not the Geth, although tbh it doesn't matter who made it.
Given that the SR1 wasn't using a Relay to travel to the system in the ME2 intro there's no way of predicting where it would exit FTL. What are the odds of the collector ship just happening to be looking the right way, at the right time?
If you watch the intro, Pressley says that they haven't found anything despite patrolling "up and down this sector" for four days. It is of course improbable that they would look at precisely the right place at the right time (although if they are using automated optical sky scans this becomes more likely), but they may well have crossed paths a dozen times already at this point, and this was just the time when they happened to luck out and spot the SR1.
I agree that it's not beyond the Collectors/Reapers to have some alternate detection method (something that detects active drive cores or whatever), but I don't believe they do until we get some kind of actual mention of their magical detection capabilities, as opposed to just kind of secondarily inferring it like we are here.
There's also the other point I was bringing up that the reason the SR1 was destroyed was not just to get a new ship, but also served a dramatic point, but it would appear you dropped arguing against that.
I don't think I ever did initially, I just said that the SR2 didn't really have to happen for the plot to happen the way it did. However I kind of felt that it was a cheap intro mainly because of Shepard's death. He should have escaped but been mortally wounded or something like that and stuck in a coma for 18 months. But having him dying and resurrected after colliding with a planet (whose gravity and atmosphere is definitely present, you get the stats on the planet with the Normandy crash site DLC...) raises a lot of questions about how, exactly, he could possibly be brought back to life months after dying, when according to Jacob he was "meat and tubes" when they recovered him. With memories and skills in-tact, no less.
Your personal favourite alternative idea is one that relies on everyone in authority on The Citadel being pants on head retarded?
But it doesn't. Sovereign even needing to be there is just something I'm assuming to be generous, that he somehow has to do something while on the top to make it go, as opposed to just the datafile unlocking it. But the events of ME1 could have gone like this if they didn't attack Eden Prime:
1. Saren gets datafile to manually open from Sovereign.
2. Saren schedules a meeting with the council, for whatever reason
3. Saren is on board, talking to the council about something, then suddenly Sovereign warps into the Citadel, rushes past the ships guarding it and attaches himself to the top of the Citadel to do whatever he needs to do. At approximately hte same time, Saren uploads the datafile to the console (which takes like 2 seconds).
The console that Saren needs to upload the file too is literally right at the place you address the council. They won't even know he's doing something wrong until it's already too late, and nobody on the citadel has Vigil's datafile to coutneract that thing.
You can make adjustments to this plan as you see fit, i.e. if something they found on Eden Prime was somehow necessary for Sovereign to know what he had to do (even though you'd think manually opening the relay that the Reapers built would be something they know how to do), he can still get it done before he was stripped of his status. If you think that Sovereign alone wasn't enough to rush past the Citadel defense fleets (even though after he was already attached to the top he could sit there and tank bombardments from the entire Arcturus fleet for like 10 minutes and only died because his shields dropped when Robo-saren died), then you can still include the Geth assault in this plan, with all of those Geth ships attacking simultaneously.
The central issue with the plot is that they never explain why it is that Sovereign couldn't have done something exactly like this prior to finding the Conduit. Obviously after Saren got his spectre status revoked it was the only option, but the point is he had an easier option that was open to them for decades. They could have done it at any time after Saren found Sovereign, which happened ~20 years prior to ME1. They could have easily patched this hole by including something about how Sovereign only conjured up the open-relay datafile after they raided Vigil's databanks on Ilos or something like that, but Sovereign wasn't even on Ilos, he was away with the Geth fleet poised to strike the Citadel and Saren was just rushing to the Conduit and never even noticed that Vigil existed (because Vigil only revealed himself to Shepard and Co).
An alternate plan involving Saren claiming that Sovereign is an in-tact Prothean dreadnought is an amusing thought experiment. Any science team that goes onboard to investigate it for any length of time will become indoctrinated, after all. And unless Sovereign starts talking to people, they have no reason to believe it's an A.I. starship, or that it is a Reaper. Getting it to form part of the Citadel defense fleet, or parking on the Citadel shouldn't be very hard as long as Saren/Sovereign are patient (and given that Sovereign waited 1000+ years already, he must be!).