In item 1, just ask for "certified copy"
Item 2 has to be more specific...what details are you asking for ? Are they on record ?
Items 3 and 4 might not be answered by the
PIO. Be more specific - ask for "certified copies" of the dispatch/receipt register, etc...
Item 5 just ask for a copy of the full file or files, including all records, documents, file notes, correspondence, on this subject.
Item 6 remove the first part. Just ask for certified copies of rules and regulations which allow official communications of the department to be sent without........., ......., ....., etc.
(I suggest also ask for certified copies of those 4 letters that you received).
Item g to l - just ask for inspection of all records, documents, files, etc. concerning the enquiry ..........
Item n and o become redundant.
Item m seems to be very general about all enquiries. May be denied by the
PIO. Try to reframe the query.
Item p and q will also be denied - since it is not on record. May be that information is in the visitors register but how long are they kept for. If you want, you can ask, but it will make the application long and also make it sound very frivilous.
Item r is definitely not information. Just ask for a "certified copy" of the letter. That is proof enough for you whether it is "official" or not.