2004 Kia Sedona timing belt repair

I've been told by a dealer that I need to replace the timing belt, and also get a tune up. This will cost me a fortune; however, in the owner's manual, it is past the recommendation of the belt replacement, so I know I should go ahead with that. What else is involved with this repair? Should the water pump be replaced at the same time, and should that be included in the repair cost/estimate? Also I have not had any performance issues that would require a tune up. Do I really need this or is it a money making ploy? What should be waring signs for the need of a tuneup? Thank you.