Hi, Bob.
I was first diagnosed when I was 63 years and had non--nerve sparing RARP. about three and a half years ago. I can't get any natural erections and this is likely to be permanent. However, I can get erections sufficient enough for penetrative sex with the aid of Invicorp penile injections.
https://community.prostatecanceruk.org/posts/t29845-Hooray-for-Invicorp
Prior to diagnosis I was getting up about three times a night to urinate. I was found to have a enlarged prostate (BPH) which was probably the cause of this. This disturbed sleep made me feel fatigued. I also started to get erectile dysfunction.
After surgery I still get up two or three nights a night to urinate and I'm still as tired. I don't know how much or the nocturia, erectile dysfunction and fatigue can be put down to prostate cancer, as the majority of elderly men without the disease, suffer similar problems.
I hope your condition improves, mate. 👍