The right base for a gravel patio
There can be lots of opinion here so what type of fabric to stop weeds? Just about any landscaping type will work as long as it is permeable (water can drain through).
Do you need to tamp the soil? If you like playing in the mud go ahead but clay will move around and sand really doesn’t need it.
When you talk about base and top that’s up to what you want.
I use crushed quarry rock or shale and a plate compactor the thickness 2-4” will be fine for most locations if you have a lot of mud maybe more.
You want the fines in the rock they help things to lock together.
Never use crushed river rock it will not pack well it moves.
If you want a decorative top rock spread it pack it and keep adding until you have the look you are after. If you want stones put down a inch or more of sand to bed your stones or pavers, fill spaces with sand and that’s it.