People with normal PSA's have cancer and people with high PSA's do not, so the PSA is a rough guide to prostate health. Its used in conjuction with other things like DRE, biopsy, pt age, etc, to determine what is going on with the prostate. I think the fact that his PSA is so low would indicate his cancer was caught very early. Thats a good thing. Im not sure if the biopsy from the TURP would not be a good as from a TRUS. That a good question for your urologist. It is true that a DRE can elevate the PSA. I would also think that the free PSA to be higher. Thats another good question for your urologist.
Your husband is lucky to have you !