A good place to start is at: http://www.cheresources.com/pnuconvey.shtml which is a fairly striaght forward basic guide. Most of your questions can be answered by looking this guide over and do the basic calcs.

First off some key aspects: what tis the maximum particle size and its density, this will determine the minimum carrying velocity, and it is different in dilute phase or dense phase.

the choice between dense and dilute is usually made based on the material characteristics dense being easier on the particles.

As to how to measure flow and pressure, the simplest way is to use a pressure gauge on the blower inlet (vacuum system) or outlet (pressure system) this will give the basic system pressure. The blower energy draw (hp or KWhr) will give the rough flow. If precise flow is needed there are many different kinds of flow meters (rota meters, Dp meters, etc. that can work - before the product is inserted, or after it is withdrawn). ■