I do understand the worries your dad is causing you. Probably his earlier release from the hospital was at his own intent. It seems that his doctor’s instructions was for him to stay longer (surely with the cathedra in place), but old man do not like to be “told” of what to do. In any case if he doesn’t have pain and passes urine normally then one should think that the healing process is OK. However, he may be experiencing incontinence and uses pads.
In a worse case urine could cause an infection and such could cause a stricture at the urethra sphincter and he would be agonizing with pain or even stop voiding.
If such happens your dad should be rushed to the hospital (emergency) because he could get kidney failure due to an overflowing bladder. Stubborn 85th do not express pain so that you may need to keep an eye on him to check if he urinates.
Physical exercises such as gardening should be fine if it is mild. He must avoid contracting any infection. I do not know his fitness with regards to his age but exercising is good to counter the effects from hormonal treatment (walking and golfing has helped me). Fatigue will be a nasty one and so it is forgetting things and hot flashes (menopause like symptoms).
Proscar (finasteride) is used to treat benign prostatic hyperplasia which was part of the problem that took your dad for the TRUP, but it also is used in the hormonal treatment protocol to lower dihydrotestosterone. He can continue Proscar as it will help in the treatment. Just follow his doctor's recommendation.
Hormonal therapy resolves in killing the cancer by starvation. To that intent patients take drugs to lower the levels of androgens circulating in the body that are the “food” in which responsive cancer survives. Zoladex agonist will “close down” the factory of testosterone (the testes) causing chemical castration. The Casodex antiandrogen will try to stop the feeding of androgens at the cells receptors (closing their mouths) and Proscar will stop the produce of dihydrotestosterone which is a variant of testosterone but tenfold more powerful (small quantities but very potent).
This combination is called total androgen blockade.
Nevertheless, not all the protocols use the three drugs. Some cases do well with only a single blockade at the testes (Zoladex, Eligard, Lupron, etc.). In some a double blockade with Zoladex and Casodex works better. That will be figured by experience along the treatment.
Your dad needs to take periodical PSA tests (every three months) to check for any cancer progression. A testosterone test will indicate if the drugs are effective in maintaining your dad on castration. This can be done every six to twelve months.
The medication for blood pressure I take has not interacted with the hormonal drugs. You need to convince your dad of taking the medicines as instructed by his doctor and doing the annual health check-ups of the lipids.
After three months on Zoladex, the PSA will drop to zero levels indicating a hit on the cancer and the start of the control in its advancement.
I hope the above gives you some insight on what to expect.
Your dad is fortunate for having a lovely caring daughter.
Wishing you peace of mind.