Need Help with Editing Music Video Concept

Here's the most efficient workflow in a couple of rules.

1. Do not use After Effects to edit your video.
2. Do your final edit in an NLE.

A cut on the beat is often less effective at generating emotion than a cut before or after the beat. The timing of the cut depends on the composition of the shot, where the center of interest is, and what comes before and after the cut. A simple example is a two-camera shot of a man and woman talking to each other. Turn off the audio, change the cut from one person to another before the blink, then cut the same scene two frames after the blink, and the mood can quickly change from loving to arguing, from peaceful to tense. Take a lesson from Jackie Chan's technique for cutting fight scenes. Precisely matching the timing and position of the fist from the wide and tight shots of a punch is much less effective than cutting to the close-up a few frames earlier than in the wide shot in real-time. Finessing the timing is incredibly inefficient in an effects timeline with 50 or 100 shots in After Effects. 

Use After Effects to create your effects. I've cut many music videos full of complex visual effects. It is not unusual for me to end up with dozens of comps with five or ten-frame handles on each shot so I can fine-tune the edit in an NLE. I almost always pre-render those effects, including transitions between multiple camera angles. I've produced a few where every shot was a separate AE comp. I've never cut an entire video longer than 10 or 15 seconds using After Effects. It's just too difficult to tell the story you are trying to tell with an app never designed as an editor.

I hope this helps. 

Hello balian_2014, the question ends up being too open. but let's try

-> Synchronization: What’s the best way to sync visuals with the beats and tempo of the music?

Markers you can synchronize your animations with markers, which involves a bit of programming, or scripts (I'll talk about this in the third question.)

There are some effects that synchronize sound waves, such as Generate>Audio spectrum, they are very common, but they have effect limits.

Visual Effects: Any tips on adding sleek, modern effects that match the energy of the track?
It then depends on the needs of the project, I recommend a lot of research, behance, Motionographer.com, Vimeo.

After Effects Tools: Are there any plugins or tools within After Effects that can help streamline the process? Aescript.com is a good place, it has Beat Edit, AudioToMarkers (Perfect for speeding up marker creation), Beatnik, and if you look there, there will be a lot more things. This part depends a lot on the expected end result, as there are also a series of other tools and plugins, like Red Giant Trapcode Sound Keys for example.

If the project were mine, the first thing I would do would be to look for and approve static references, and then think about how to put them into practice.

Good job!!!