Opinions vary, but in general: If your soil is extreme (rocky / nothing grows well in it / always wet), then deeply amend the entire planting area, or dump good soil thickly on top and plant in that.

For single planting holes in otherwise decent soil, just use the native soil and place the compost on top.

A Japanese Maple should not need staking -- that is for new tall spindly or top-heavy plants. If a new planting is subject to nearby mowing or running animals, place some fencing around it.

This website is an easy way to access USDA soil surveys-

https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

University level studies were showing that amending of planting hole backfill during planting of woody plants was counterproductive by the 1960s. It is not a matter of opinion, it is a repeatedly duplicated result of organized experiments conducted by serious investigators over a period of decades.

Replace bed with different soil or do not make any changes to existing soil. Do not mix different material into a small area like a planting hole, or mix organic soil amendments into an area intended for long term plants like this or other trees, shrubs or peonies for instance. Vegetable garden style soil preparation and management is for vegetable plants and flowering annual plants. Even then only a comparatively small amount of material should be used.

Japanese maples are very common in local plantings, chances are there is no need to modify the rooting environment of your planting site. Their main requirements are that the soil drain well at all times, yet not be prone to severe drying out. And like other maples a certain minimum level of fertility is needed (the presence of maples on a site in nature tends to indicate the soil has fairly high nutrient levels).

Stake for one year if it looks like the tree will blow over otherwise.