1) As a Moore fan (back then, anyway) I was excited about this story, especially with Swan, Schaffeberger and Perez on art chores. I think it still holds up quite well. At the time, it was just one of those Moore stories full of goose-bumpy moments and a nicely handled, growing sense of dread...with a happy ending at the last moment (for the record, this is how I like my stories...dance around the edges of darkness if you like, but don't wade hip-deep in misery and depravity just for the heck of it). I had no idea it would end up actually being THE LAST Superman story for many, many years.
2) I was unconvinced in 1986 that DC in general needed a reboot, and I still think it was unnecessary. As for Superman in particular, I was willing to approach the reboot with an open mind, and I still have the issue of Amazing Heroes that came out a month or two before MOS #1, and which I pored over in detail more than once. I liked that Byrne liked the old TV show (at this point I didn't realize his ENTIRE knowledge of Superman came from films and TV) and some of his other plans were intriguing. I also looked forward to his teaming with Dick Giordano and...joy!...Terry Austin, since I had by then come to loathe Byrne's inks over his own pencils (I dropped the FF until Ordway came on to clean up the art).
I was unimpressed with MOS, which I found light-weight and padded. It was so simple-minded it felt like one of those Power Records comics of the 70s. Superman #1 was a bit better thanks to Terry's inks, but the writing was on the wall already; Superman is lying face down and beaten on the cover (of his own first issue!!!) and spends the whole book getting his clock cleaned. After that, there were very few bright spots. I didn't mind the Lori Lemaris story too much (since it was pretty much a remake of the original) and I was okay with the first Mxyzptlk. But there was also Supes sleeping with Amazing Grace (ick!) and killing people on Apokolips, Bloodsport killing everyone in a McDonalds, Superman making a porn movie with Big Barda (what the...?), the abysmal "Pocket Universe" travesty and the piece de resistance, the murder of the Phantom Zone criminals.
So, short answer: I was ready to like the reboot, but that wore off fast.
3) One of the low points of comics, period. The murders are bad enough, but they come on top of several issues of the most bleak, hopeless, gruesome storyline ever printed. A whole planet of people destroyed, all heroes killed, yadda yadda. Byrne bent over backward to create a situation where Superman would "have to" kill. That anyone could even imagine such a hopeless, dark scenario is bad enough; that he could take the time to draw it all is even worse. That someone at DC thought a person with such a mentality was in any way suited to write Superman is just sad.
4) A cheap stunt, unworthy of the character. If you're going to kill Superman, let Lex Luthor do it, or even Brainiac, not some 5th-rate non-character invented for that specific purpose. The death carried no emotional weight whatever. The ultimate irony is that DC got what they wanted -- extensive press coverage -- and it backfired on them. There are people who think Superman is still dead and has not been in print since 1993. In the immortal words of Nelson Muntz: "HAAAA-HA!"
5) Avoided it like the plague.
6) Not a very interesting book. I liked the proposal, but by the time of the wedding I'd quit collecting and just bought the album as a one-off. The art was pretty choppy throughout...even the Swan and Cardy pages were a let down. Ultimately not the big thrill you'd expect after 60 years of build-up. And I think most fans agree, a bad idea to boot.
7) I was long gone by the time of the blue suit. I will say, though, that its presence in the earliest issues of JLA kept me from ever collecting that title.
I have to confess I haven't read "Birthright." From what I know of it, it sounds okay. But as the song goes (more or less) what the world needs now is another Superman origin like I need a hole in my head.