2 and 3
Why are 2 and 3 in text - can’t detect much sound they add??
Not sure about the sound but these two numbers are used in place of sounds that usually not found in English.
The (2) is used as a glottal stop. I think in English glottal stops do not occur in the middle of the word, normally, but they do in Arabic. Thus, some people invented this method of typing this glottal stop (personally I would prefer using "'" but probably "2" is clearer).
The same thing with (3), which is a sound not found in English at all and it is pharyngeal. Maybe this youtube video would help (but I didn't watch it really, some people said it is good): https://youtu.be/Y0ro6b50-Lk