I gave it a 7/10 so definitely not bad, but...

1) Why is being gay such a big deal in 2018 at this high school and why is there only one other known gay student (a very obvious, effeminate "queen")? Again, this is current-day.

Who said it's a big deal? The student body are all mostly very accepting. When they find out, they don't take it as a big deal at all. However, there are those 2 jocks who give them a hard time and torment them. Simply because they're dicks. Notice he tells his friend Abby before he tells his family. Because one of the things he's most unsure about is how his relationship may change with his family. He tells them "I'm still me". As Ethan explained one of the things thats hard for him is his mother acting like he's straight when talking to their family members. Simon just doesn't want his relationship to change with his dad or mom. He also says one of the reasons he didn't want those e-mails leaked is because then "blue" would get scared off. Simon also says how he doesn't feel comfortable about "having to come out" because its not like that when you're straight. So why does he have to?

2) The principal/guidance counselor (or whoever he was) was way over the top and a typical movie character they put in high school movies that doesn't ring true whatsoever.

Don't agree with you at all. There are many teachers and vice principals that are upbeat and lively like this.

3) When they tried to mislead us as to who the unknown correspondent "Blue" was they would show possible scenarios for each person he suspected, but when they showed the actual person they showed a white guy typing (without showing his entire face of course), which was hinted at being the actual guy, yet it turns out to be Bram, who is black.

These were the thoughts of Simon the entire time. So its what he was envisioning in his mind. He thought it was Bram so thats who he was thinking of. Then that got erased when he saw him with the girl about to have sex. So he shifted to someone else, etc.

4) Why was Simon's bff girlfriend Leah so upset that he told her she should date Spencer? How was he to know she liked him (Simon)? I don't get her outrage.

Who tf is Spencer? His name was Nick. I don't know how you can't understand how she was upset. It was very obvious and he did know. It was very hurtful to her as she was in love with him. Idk how you can't understand her being deeply upset. He didn't just tell her he was gay, instead he told her to go out with someone else when there was really no interest there. He was leading his best friends towards lots of dead ends.

5) And is making it both a gay AND interracial thing perhaps too much of a stretch when trying to reach a mainstream audience to accept being gay as no big deal in today's world? I mean, perhaps many conservatives will see this as too much of a liberal push.

Who cares? If they can't accept it then too bad. The movie preaches acceptance of others. If they can't accept homosexual relationships or interracial relationships then too bad. That gripe is really ridiculous.