Welcome to comics! You’re asking the right questions haha!
So…bottom line is that it can get pretty confusing at times. Yes, while Infinite Crisis is a sequel to Crisis on Infinite Earths, you should be able to enjoy it on it’s own, although you may be having some questions, like who exactly is Superboy Prime. And what I’ll tell you, is that that’s totally fine. I’ve been reading comics for quite some time and still run across things I couldn’t tell you the origin of. But somebody on these forums can.
The “Crisis” series is an important benchmark for the universe. The first one, Crisis on Infinite Earths, rewrote the continuity of the time. I’m 31, however, and that series was before my time. I’ve grown up in a completely “post-crisis” world, so it can be difficult to put that series in context. Also important to note is that they weren’t planned with each other in mind. Each is written by a different writer, putting their own spin on things. It helps to remember that things are continually being reinvented. It’s bewildering at first, to be sure, but it keeps things fresh and progressing. And if you don’t like some current (Snyder) iteration of something, it won’t be long before the next one, so just relax, there’s always something else coming up.
The entire Crisis series, however, is:
I. Crisis on Infinite Earths (historically important)
II. Infinite Crisis
III. Identity Crisis (this is kind of the odd one out, but can be read on it’s own, recommended)
I.V. Final Crisis (this one is divisive, I enjoy it, but for somewhat abstract reasons)
So…I would actually recommend Blackest Night. You seem to have enjoyed Geoff Johns, so I would give him another shot. Just read the main series. There can be good tie-ins, but especially when first starting, don’t burn yourself out on the completionist stuff. Read a few big events. Take some recommendations on a favorite character. The boards are always willing to provide recs.
Anyways…hope it helps. Welcome to comics - it helps to embrace the insanity.