Planning to buy a small air compressor but not clear what exactly; it could be even one of those used to inflate tires.

I want to clean PCs / equipment gently but effectively and I want it to have a small tank (reservoir?). It will be used for an aerograph and small air-driven machines.

My questions:

How do you call in English the valve regulating the pressure at the output?

I want it adjustable so how to tell what range it should cover?

Those 12V units, are they worth the expense?

What else to look for besides a filter / water trap?

Oil, is it a no-no for what I want it?

Found what locally is called "dentist compressor", fitted with a tank and small in size.

Always took for granted compressed air. Now I know that I know nothing about.

Please, few short sentences preferred than googling and reading long articles. Little time available here. Believe me. \clipart{angry}

The local tradition in the shipping business say that by December everything slows down. Not true. Full ahead as ever. Always. For years.

Why people insist in repeating legends? \clipart{uhoh}