It goes without saying that this is one of the most popular tourist spots in Canberra.
There are many architecture images available here. Because the building has been designed to be light and airy, you won't need a flash.
There is only paid parking available here, under the forecourt of Parliament house. There are usually plenty of empty spots when I go, but it is usually not at a peak busy period.
Alternatively, you could park down near Old Parliament House and walk up the hill, but you'll still have to pay to park.