Cadence is also a personal preference, lower cadence is more based on muscle power (50-70 rpm) higher (90 rpm+) put more load on your cardiovascular system. In time you’ll drift towards what feels natural for you Going up hill try experimenting with the cadence. You’ll quickly discover what cadence you feel is efficient for you
In regards to your gearing question, it is hard to tell, it’s about ratios between the number of teeth on the cassette and chainring. Find an rpm you like, adjust gear until you find that rpm
Try playing around with the pressure. Find what you like. Suspension is a real speed killer, on even surfaces. With every pedal stroke you compress the suspension, and that power doesn’t make it to the rear wheel. If you don’t have a lock out, adjust to as little suspension you feel works for you.
There are a lot of rules of thumbs, but in the end it needs to work for you. Stiff suspension and hard tires will give you speed, soft suspension and soft tires give comfort