I'm fine with a dry run down as long as all the major plot points are hit. But a voicey synopsis is more fun to read.

Harsh truth, maybe the book you're querying isn't hitting the market at the right time, or your writing just isn't quite there yet.
Write the next thing. Keep striving. Keep working to improve.
Most successful writers aren't necessarily the most gifted, but the most determined.

It's helpful, if used properly. It's great for networking with other writers which helps when asking for blurbs. Can't say if it helps with sales, really. Sometimes?
I've also seen it backfire. You've got to be careful.
Tread carefully & treat your tweets like mini-press releases

Mention your self published work by title and how many copies it has sold. Especially if it's sold over 5k copies. (The 1st thing I'm gonna do is go check it out on Amazon).
If you don't mention sales I'm going to assume it was around 500 copies or so, which is the SP average.

Hmm...Adult humored as in sexy time humor? Then probably a pen name is a good idea.
Use your real name in the query, and put "writing as [pen name]" next to your signature.
You can have a convo w/ your agent about if it's necessary when submission time comes

I've not had first hand experience with this, so I don't know. I don't THINK so?
As long as the book is in English, and reads grammatically correct, then it should be fine.

Depends on the publisher. Fairly typical but not universal.
They usually want book 2 w/n 6 months, which is TIIIIIIIIIGHT. If you need more time, have your agent ask for it. I'd say 12 months is the most they're going to give you, though. Tops.

Stand alones sell too and a great many books work better as a stand alone, imho.
Don't sweat this.
Just pitch your book. No sense in forcing a series if it wasn't meant to be one.

There are some agents who rep self pubbed works. I do not. For me, the best time to pitch me would have been before you self published. Do some research into agents, it's not a deal breaker for others.

I don't require social media from my clients & I have signed some who don't participate, but many publishers like to have authors who have one.
I'd say MOST of my clients are on social media. It's not a deal breaker for me & I think the pubs who require it are outdated.

That the writer doesn't send a synopsis, but another pitch paragraph.
I want beginning, middle, and END, spoilers and all.

I'd let them know.
They may pass for the very reasons you've just fixed in the revision.

First pass = read query letter. Reject or goes to 'Maybe' pile.
Second pass = read synopsis. Reject or goes to 'To Read' pile.
Third pass = read sample pages. Rejected or requested.

I say go for it. Those who don't want responses have likely disabled the "reply" function on queries.

I'm very non-sporty, so I'm not the agent for that manuscript. However, I've seen editors specifically request sporty manuscripts, so there's a market for it.

Depends on the agent. For me, I can be heavily editorial to, "This is perfect, let's go to submissions," depending on the state of the manuscript.

Pitch it as a YA crossover.
Problem solved.
xo

I can't speak to this, b/c I legit have no idea.
There are A LOT of pitch events and agents can and do burn out on them, but I also know some agents who close to queries and ONLY look for stuff via pitch events, so I say, DO BOTH = query and pitch events

Nope, not mandatory.
Although some publishers looooooove those angsty YA voices.

Bashing other books is a big no no.
Flirting, also a no no.
Categorizing a book incorrectly b/c my QM doesn't have it listed - there's a reason why. That's a no no.