Jenny, let me try to answer your questions in the order supplied.
In general success rates are similar, but this is a unique case (aren't they all?). It is quite difficult to prevent overspill of radiation into the b!adder and bowel and then again, I understand surgery can be tricky with anterior PCa. I would say you need the views if a Urologist and an Oncologist to help in decision making, based upon what a CAT scan shows.
On exercise, not only can your husband exercise whilst on HT, he will need to. The treatment tends to lead to weight gain around the hips and belly, so increased exercise is essential.
Usually, RT does not target the lymph nodes. Too far away for effective focus on the prostate capsule, I think. Certainly, the point was never raised in my treatment as a possibility.
I had no problems driving to and from my RT and no discomfort in nether regions.
The HT is intended to cut off the supply of testosterone on which the PCa feeds, so the expectation is that the tumour will be reduced in size and hopefully disappear. There are no certainties, as every case is unique. From what you report, the aim of the HT/RT combination is curative.
As to the holiday, you need to ask when the RT is planned. It could be either side of your holiday or after it, I imagine. Only you and the consultants can sort that one out, but I would hope they would have regard to the beneficial effects of the holiday as well as the need to progress the treatments in a timely manner.
I wish you both luck and hope the treatment goes well.