[bigboki]

Watch some of the setup videos on youtube.
Use fret rocker - if you don't have one use credit card.
You need to check each THREE (not four) frets at the time.

Let me find out some setup videos for you

I think this one will be perfect for you:

also our Torontonian has a great setup videos - there are A LOT OF Them,
Dave's World of Fun Stuff

if you need more help dont hesitate to ask (or even PM me).

 

[bigboki]

I just check all the frets with a straight edge three at a time and there’s some rocking when the middle of the three frets is the 2nd, 7th, 9th, 12th, 14th, 16th and 20th frets... it’s hard to check up to the 24th fret because the frets get too close together for me to look at just three at a time.

also when you are checking rocking - you should check in three places - high / low (near E strings) and middle.
If you have rocking like this that means your 2, 7, 9... are a little bit higher than the rest. Also depends on the amount of rocking if it is tiny - almost unnoticeable , that's ok, but it is more then that you will need to level the frets.

The more rocking you have the higher action will have to be to avoid dead spots.

Regarding truss rod adjustments, no that could not cause this kind of fret issues (all over the place).

hope this helps