97 Camry V6, I threaded the rear cam (by the firewall) bolt in and lightly ratchet the bolt in and the cam snap forward a little bit. Did I do any damage Is the V6 non-interference?

 

think you should be ok

check the cam bearing caps if worried

check those valve lifter alignments to the cam lobes


severe damage such as valves hitting the pistons = bending pistons
only when the engine is running at high rpms breaks a timing belt or skips a tooth

 

I don't want to tear the whole engine apart. Once I get the timing belt on I will rotate the engine slowly a few times to make sure it turns without any binding.

 

The V-6 prior to VVTi is non-interference. And even if not so you are not going to damage anything by manually rotating the crank or cam.

Once you get the belt on, rotate crank 2 times CW and recheck cam/crank pulley alignment.