Trim and Tilt

[HD]

After years and years of fishing....I bought a boat that has trim and tilt.

First question:
Do you change the hydraulic fluid in it every year?

Second question:
How do you check it?
(I'm assuming with it tilted all the way down and pulling the higher fill plug)

Third & fourth questions:
How do you use it? (other than it lifting the motor up and down) Do you adjust it while you are motoring?

Any helpfull hints would be appreciated,
HD

[The General]

With the power trim I will adjust it while on the move, usually while a WOT. 

[DDSBYDAY]

    The trim is easy to determine by steering.  When you have it right the steering is effortless.  You will be adjusting it as you gain speed.  If you start to bounce on the wake you drop the bow.  The trim is constantly being adjusted while the tilt is more for traveling and storing.