Modifying Clauses

As a commodity, soft drinks are relatively cheap. OK.

The worker of the company, irate and frustrated, quit his job. It's OK, but you're right, there's the possibility of confusion.

Irate and frustrated, the worker of the company quit his job. Seems better to me.

The worker of the company doesn't sound too well too me, even if correct.
I'd say
the company worker.

When an modifying clause precedes or goes after a noun, does the modifier have to agree in number with the modified noun?  No. Adjectives in English have no plural forms.

ie: As a commodity, soft drinks are relatively cheap.

For example in this example, commodity is singular, while soft drinks is plural.

Also, can a modifying clause precede or go after an entire noun phrase? Yes, in some cases, but not universally and not usually.  Like this:

The worker of the company, irate and frustrated, quit his job.

It kind of looks like irate and frustrated is modifying company.  Yes, but that's not likely, so we automatically conclude that the worker is irate and frustrated.

CJ

Breez wrote:

Also, I guess this following sentence would be perfectly fine? Jack and Jim, as the leader of the club, were very good. or Lions and cheetahs, as the main predator of the savannah, are deadly.

IMO:
Jack and Jim, as the leaders of the club, were very good.
Lions and cheetahs, as the main predators of the savannah, are deadly.