Seconded here. We've done paving stone walkways and a paving stone patio and all of it turned out very well. In fact, we've had multiple neighbors stop by to ask us for a referral so they can get similar work done at their property. (We all get a good laugh when we tell them that it's DIY.) If you prepare a proper base, the rest is fairly easy and nearly foolproof.
We start with a couple inches of crushed granite. It compacts very well and provides a very level and stable base. A (rented) plate compacter is best, but for smaller projects I made a compacter from scrap lumber.
With the crushed granite in place, compacted and leveled, we add an inch or two of sand and screed it to make sure it's level.
We don't use plastic because of the potential for it to trap water. Another option might be a layer or two of heavy landscape fabric, but we've never found that anything can grow up through the crushed granite, the sand, and the pavers, so we don't even bother with fabric.
We don't leave intentional gaps between the stones. I've never seen anyone do that.
We don't do that. With a proper base, there should be no settling.
We definitely don't do that.
We use polymeric sand to fill the natural gaps between the paver stones. Polymeric sand is different from regular sand in that polymeric sand sticks together and hardens when it gets wet, so we dump a few bags of polymeric sand onto the new project, then we sweep it across all of the joints, allowing the sand to fall into the cracks and fill them up. When no more sand can fall into any cracks, we lightly water the entire project. When the water dries, the project is finished. So far, nothing has grown up between the stones.
Our way is not the only way, and may not be the best way, but so far it has been exceptional so I'll highly recommend it.