While I agree with Shri Kasturi Sethi Ji in toto, w.r.t. question No. 1, I wish to add the following from point of view of practicality:
There are certain reports which can be downloaded from GST portal from tax-paper side only and not from Dept's side. But, these reports helps officer during his audit and makes his job a bit easier.
I see no reason why an assesses should make dept. officer sweat for something which is directly available from portal. Hence, you can always ask officer which of those reports they want, download them at your end and share those reports with the officer.
Non-sharing login credentials and non-sharing of desired reports available on GST portal are two different things. While former is your right, later may not be taken kindly.
And suffice to say, law has given Dept. officers enough power/s - in so many different ways - to effectively deal with such assessee if he refuses to share even those reports (which will be seen by Dept. as creating needless obstacles - based on technicalities - for Dept's officer to carry out effective audit in a time-bound manner).
These are ex facie views of mine and the same should not be construed as professional advice / suggestion.