Yes, it was liver cancer, No we don't test every cat for FIV/FeLV. If we are dealing with a colony of ferals some are tested. All strays that come in as unneutered males are tested and also any other cats the vet feels they need to test.
Our vets always seem to get it right. Occasionally they will say we don't think it is but would like to test just to confirm, in every case they have been right, and those case they have been almost 100% sure they too have been right.
The previous owner of Frodo and Sam was a little concerned about Sam. He actually told me that a few days ago.
Frodo is absolutely fine and very happy and settled in his new home.