Don't worry about timelines, universes, canon, etc. Just Google "best Batman stories" or "top comics of all time" and take note of the stories that are mentioned often. Read those.
New readers usually fall into two groups: (1) those who must read everything in order and (2) those who are willing to ride along with any story, not letting unexplained references bog them down. I recommend taking the latter approach as the former will require more effort/time/money and make comics seem like work. It's easier to just ignore things you don't know, trust they will be explained, or just Google them if necessary.
It's great that you're interested in so many characters, but think about what that actually means. You're only ever going to read one book/story at a time i.e. one character at a time. When starting out, it's easier to focus on a handful of characters and a handful of recommended stories per character. Then, you can use those early experiences to help inform what you want to read next.
Quality varies with each writer/artist. Just because Thor story 32 comes after Thor story 31, doesn't mean it's worth reading. They could even be completely unrelated (except for their shared series title).
Check out Marvels by Busiek and Justice League: World's Greatest Superheroes by Dini. They're great first books for new readers.
This is one of the covers he drew for the series Marvels. It is now collected in trade, and features a lot of spider-man. it takes place in the 1960's IIRC as it revisits the death of Gwen Stacy