I was told that Tocoma timing belts had to be changed around 90k before they broke, damaging the engine. Is this even true? And how much trouble is it to do it yourself given mechanic experience?

DO NOT DO IT YOURSELF. Seriously, I think your Tocoma should have the 3.4 liter V6, which I have in my 2002 4Runner. Its a big production to do it. I had it done at the dealer. Good plan, right? Guess what - After driving about 150 miles, it fell off! They didn't tighten the crank shaft properly (those were the words of the mechanic I took it too near where it died, as well as the dealer, after they checked it out). Well, too bad for the dealer, they had to come pick it up (140 miles door to door each way for them) and then they did have to yank the engine out to fix the mess.

Its an expensive service at the dealer (about $500, if I remember correctly), but you can probably get your local mechanic to do it for less.