Toyota Repair: Timing Belt Replacement, timing belt replacement, haynes book

Question
Hi Paul:
  Got a few questions from a fellow Floridian over in Clearwater. I recently purchased a 1994 Camry 4 door sedan XLE, with the 1MZ..V6 engine. The car currently has 150K miles on it and seems to run very good other then the fact the Check Engine light came on a few days back with an indication of a bad Bank 1 O2 sensor. Changing those 2 sensors are fairly easy. I am concerned about the timing belt and since the seller didn't know when the belt was last changed, I may need to change it out soon. My questions are as follows:
1. Are there symptons that would indicate a need to change out the belt?
2. If I do decide to go ahead and do the job myself, should I change out the water pump, cam seals, and crank seals while Im at it?
3. Last of all, I am a pretty good wrench, and don't see the need to pay a shop the $700 asking price for the job. The only reference manual I have to go by is a Haynes manual, seems to be fairly straight forward in its illustrations on completing the job. Is it worth tackling this job myself, or is it too complicated and I would be better off letting a ASE do the job?
   Thanks for your help.........
Peace:)

Answer
the only indicator of the timing belt being bad is when you can't start the engine cause the belt broke...! seriously! 4 yrs 0r 60,000 miles!
i would replace the w/pump and  the seals when i do it at that mileage.
it's up to u if u feel up to the task, it's not that bad if you take your time. the haynes book if fine! you can do it! best of luck! just go with all toyota parts! it's life easier. paul p.