Learn English – “Straight up and down” meaning

Don't be so hard on yourself. English is very difficult.

This talks about present perfect tense - which have been by itself falls under, and have been by itself can be used to describe an experience:

You can use the Present Perfect to describe your experience. It is like saying, "I have the experience of..." You can also use this tense to say that you have never had a certain experience. The Present Perfect is NOT used to describe a specific event.

Have been + {-ing form of verb} is present perfect continuous tense, which is different. That's used to talk about something that has started at some time in the past and is still ongoing or happening now.

Putting would in front of either of these now says that the action or experience did not happen because of something. Typically a clause will precede or follow explaining why, typically starting with but.

I would have been to Japan, but I was unable to afford the trip.

I hated her guts. I would have otherwise gone to the skating rink.

I would have been going with him, but he sort of creeped me out. So I went with her instead.

We would have ruled the entire kingdom, yet their relentless attacks on our land proved it impossible.

Prepositions don't have to be part of a phrasal verb, in fact I would say most aren't. In this case, none of the prepositions have any special relation to the verb. They're all literal descriptors of the positions the subject goes through during the action.

Try to break up the sentence into the smallest chunks that make sense. Here: He fell. Yeah, that makes sense, that's true. Okay, where did he fall? Into the pool. What did he fall off of? He fell off the ledge. So now, put it together.

He fell off the ledge and into the pool.

You can leave out the "and" here, but it's still there for grammatical purposes. You can tell if you use three prepositions:

He fell off the ledge, through the air, and into the pool.

You can't leave out the "and" here, there's no way to use three prepositions without the conjunction. That means that there's no way to do it with two, either, and the "and" is still there, it's just not spoken.

Right and straight are both intensifiers, and don't really make sense to me here. There's not exactly an indirect way to fall off a ledge and into a pool.

I hope this helps.

Edit: A note to help distinguish between phrasal verbs and normal prepositional adverb phrases: phrasal verbs don't accept objects of the preposition, and they don't pair with prepositions in conjunction phrases.

The roof fell in. good
The roof fell in the house. not good
The roof fell in and onto the ground. not good
The roof fell in onto the ground. good

Does that help you see the difference a little better?