Re: Inquire about in the question vs inquire if in the answer
I always find "inquire/enquire about" very clunky in some situations and this is one of them. I would use:
He wanted to enquire as to whether Dinon had any friends.
He wanted to ask whether Dinon had any friends.
I would use "enquire about" in situations like:
I am phoning to enquire about the availability of rooms at your hotel next Saturday evening.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.