A common problem on the 3.4L V6 is that the contacts inside the starter burn up and need to be replaced.
If you can turn the key and hear the relay click, but the starter's not cranking, then it's probably the contacts.
Here's some more info about that problem:
http://www.toyotanation.com/forum/t138611.html
As for the key not turning in the igntion, the ignition cylinder is probably wearing out. That's not connected to the starting problem.
