What would make my car idle a bit to high when im at a complete stop?

I have a 1996 mazda protege its it great shape inside and out, and it only has 94,000 something miles. There are a few things i need to replace on it such as brake pads, new shocks, i would like to change out the spark plugs and transmission fluid. Now it idles a little high when im at a complete stop. What would cause this and is it pricey to go get repaired? Also like i said i need new brake pads when i go to slow down my car will shake a little, slightly no one else can really feel it but i can since i am driving it! Could that be due to brakes?