Reports, dissertations and bound documents rarely want a number on the cover, and a chapter pulled out of something larger often has to carry on from where the previous part stopped.
Leaving pages bare and choosing the first number are different things, and mixing them up is why numbering so often comes out one off. Leaving pages bare decides which pages get a number at all. The first number decides what the counting starts from.
They work together, which is what makes a section of a longer report straightforward. Skip the cover and start at twenty four, and the page after the cover is numbered twenty four. Both are needed when a document will be bound with others.
One detail that trips up other tools is a landscape page inside a portrait document. A rotated page reports its dimensions the wrong way round, so a number placed without allowing for that lands along the side of the page instead of the bottom. Here it appears where the reader sees the bottom.
You can leave any number of pages at the front bare. Everything after that is numbered.
It goes in the margin, and you can move it further from the edge or make it smaller. The preview shows exactly where it lands.
Not from the saved file, because they become part of the page. Keep your original, which is never changed.