Planning a Chipmunk build and even though I've been flying for 5 years and built several types of planes, I've never built or flown one with flaps. I thought that this was the plane to do it on. Aside from the more realistic point of view, how do flaps really work. I wouldn't want to introduce something new that could significantly increase the risk of disaster. Why are flaps used? for take offs or landings? What does one have to be aware of as flaps are deployed? Hope there can be some fairly easy answers to what I imagine can be an involved subject. Thanks all.

flaps are used to increase lift when flying slow. They should not be used as a speed brake. The plane may pitch up or down or not at all (no trim change). There is a little extra drag that will allow you to make a steeper approach without gaining any speed. Every plane should have flaps, imo. They are not optional.

I would add flaps to any high performance aircraft. The reason for this it makes the landings much eaiser and will reduce the chance of "tip stalls". Now with having said that let me make myself clear, what I am saying is actual flaps on the inboard portion of the wing, not the electronic version of flaperons.
Real flaps increase the camber of the wing lowering the stall speed of the aircraft a bit alowing for a more gentle landings. Even more important they alow for you to make a steep aproach without gaining speed if you have obstructions near the field. They generaly expand the envelope of operation of the aircraft, they are an enhancemant, but typicaly not required.
Now generaly they are used for landing but can also be employed for takeoffs also, to do this you have them up as you start your takeoff roll and the as you reach V1 you give it 15 degrees or so for the climbout.
I have added them to a couple of my planes to tame the landings a bit but they are very high wingloading scale planes. The result was that I could make my aproaches less shallow and at a bit lower speed, and the added drag makes them slow much faster, for a shorter roll-out on landing.
Good luck and have fun, keep in mind I did it "just because I could" not because I had to....

When the flaps are lowered, it effectively gives the wing washout. This is why the plane is less likely to tip stall. You can also temporarily give the wing washout for a landing by reflexing the ailerons upward. This works for fractional span or "barn door" style ailerons, not full span ailerons. Lowering the flaps and reflexing the ailerons at the same time is called "crow" and is used a lot on ultra clean sailplanes for glide approach speed control or diving out of a huge thermal without the airspeed reaching wing flutter levels.

I had flaps on a Chipmunk some years ago and found that I never used them. On this particular plane they add unnecessary weight.

If your plane is too big and the runway is too short, flaps may be the only way to land in the space available. I had a .60 glow size semi-scale plane with flaps and they did not make much difference because the runway was plenty long. If you want to deal with additional complexity and weight, install the flaps. My plane was destroyed while doing a low inverted pass. I accidently hit the flap switch. I'll sell you the flap servos real cheap.