Vers 8.x compatibility

Hello:

php v 8.x questions
https://www.php.net/manual/en/migration80.incompatible.php

The ability to call non-static methods statically has been removed.
Thus is_callable() will fail when checking for a non-static method
with a classname (must check with an object instance).

Q: does this mean that calling a class method with self::methodName()  from within the class will not work?

I assume that static methods have to be declared as such or am I misunderstanding ’static’ methods?
I seem to remember the use of $this in a method  makes the method not static. I define all of the
methods I write in such a way that they never rely on $this or non static variables.

One other question:
In Googling php v8 I came up with a reference to the v8js. This is the first time I have encountered it.
Is there a publication that will address it in greater depth than I could find on the php manual pages?
It appears that it essentially does eval on js code strings and shares the result with php. Am I on the
right track?

Thanks for time and attention
JK