the usage of "as well as"

Dear Sir/Madam,

Thanks for taking my inquiry. May I ask the usage of "as well as"? Merriam-Webster uses this phrase in two ways: as conjunction and as preposition. My question is, when “as well as” linking two nouns functions as the subject in a sentence, is it defined as preposition more often (with a comma)?

examples like these:

the coach, as well as the team, is ready (M-W)

The National Guidelines Clearinghouse and SAGE directory, as well as guideline developers' websites, were also searched. (COCA)
(Is this sentence wrong? Since the verb should go with the first noun)

But is it also common to use “as well as” as conjunction to link two nouns (without comma) and the whole phrase functions as the subject of a sentence? And in this case, should the verb go with the first noun or the second?

So far, I haven’t found any example sentences of this usage in online dictionaries, only found few in COCA.

Scores for students exposed to the universal preventive intervention as well as students exposed to the control classroom management procedures were identified and compared.

All costs associated with both an inpatient day in hospital as well as per-minute use of a burn treatment room were calculated using a bottom-up microcosting model.

But I’m not sure if it’s correct or standard.

Looking forward to your reply! Thanks a lot!