和 read huo has four pronunciations:
Liang’an defines neutral huo as:
and gives the following example words:
The definitions of the other pronunciations of huo certainly don’t fit. Why? Well because:
huō can only be found in the word 傻傻和和 which means stupid.
huó basically only means: to mix with ...
Yes, 4-2-4 is correct. According to the sandhi rule of 一
i.e. 一 should be pronounced in the 2nd tone before the 4th tone.
And the sandhi rule of 不
i.e. 不 doesn't change the tone (the 4th tone) before the 1st/2nd/3rd tone.
BTW: 2-2-4 sounds weird to me.