The serrated knife should be 8-12 inches long and not too flimsy, great for carving roasts and cutting bread.
The chefs knife is the big chopping knife, it should be 7.5-10 inches long and of a good weight, not too light and flimsy, you will then have better control. This knife is great for just about everything, if you keep it nice and sharp.
The paring knife should be about 3 inches long and is great for little jobs, like peeling.
Having a sharp knife is very important when cutting. I use an electric knife sharpener. The steel rod you see chefs use is just a temporary solution, it only straightens out the knifes edge, it does not really sharpen it for the long term.
I have ChefsChoice model #120, it’s not cheap, about $160, but really worth it for those that cook a lot or those who just want a sharp knife when you are ready to use it. I have seen them at Costco.
There are other manual sharpeners out there that work pretty well too, I just thought I would let you know what I use. The link for this sharpener is below.