The basic answer to all this is no they can’t, but it needs to be broken down a bit.
– a member of the EC can’t ask for those kind of details, they don’t have any right to ask for it. They are just a member of the EC. Unless they are authorised to ask, they can’t ask, and anyway most of what they are asking for you are not required to provide (see below).
– if you are an owner and you have people staying there with you on a temporary basis, or someone is looking after it for you, presuming there is nothing in the by-laws, you do not have to provide any information about that to the OC.
– if you are leasing the unit to someone, either all of it or part of it, then you have to notify the strata manager under section 119, within 14 days. But all you have to give them is the name of the lessee. You do not have to give them a copy of the lease.
– I am not sure if there is anything in your by-laws or Council requirements applying to the scheme, but in the absence of that (and assuming there is enough room) there is nothing stopping you having a flatmate.
So – if you can’t find anything in the by-laws, I suggest you tell them to take a flying leap, as politely as possible. Sorry, but this kind of thing really makes my blood boil.
You may also wish to consider advising them that you consider their actions an invasion of your and your friends’/associates’ privacy and your right to peaceful enjoyment of your property, and if they do not desist you will have to consider your options.