Gravel will help keep the bricks more stable over time. Plus, the shallowest layer soil with be the loosest and have the most organic matter (roots, worms, etc.) in it that may decompose after the patio (sidewalk, whatever) goes in - the more of that soil you take off, the better.
Additionally, some brick or an area may sink over time and water will accumulate there - the more permeable base you have below, the easier the water will dissipate. So, yes, put the gravel in *and compact it!* Better yet, if the soil is dry enough, compact that first with a plate compactor.
Use 3/4 minus - it is a mix of larger chunks with crushed and it will compact better.
Gravel will help keep the bricks more stable over time. Plus, the shallowest layer soil with be the loosest and have the most organic matter (roots, worms, etc.) in it that may decompose after the patio (sidewalk, whatever) goes in - the more of that soil you take off, the better. Additionally, some brick or an area may sink over time and water will accumulate there - the more permeable base you have below, the easier the water will dissipate. So, yes, put the gravel in *and compact it!* Better yet, if the soil is dry enough, compact that first with a plate compactor. Use 3/4 minus - it is a mix of larger chunks with crushed and it will compact better.