Sqad's input will obviously be far more valuable than mine but, as I've got prostate cancer myself (and have therefore boned up a bit on the subject), I'll throw in my tuppence worth anyway.
Firstly, a bit about PSA levels: In a man under 50, a 'normal' PSA level is under 5 but for those who're are older, it might get up to around 8 without causing any real concern. So 14 is definitely worth investigating but it's nowhere near as high as some can be. (My own PSA level, at the time of diagnosis, was 135. Someone has posted here about their father-in-law having a PSA level of 314).
My own prostate cancer was discovered when the tissue from a prostate reduction op was looked at. (So, unlike your father, I'd already had a biopsy performed before the word 'cancer' was mentioned to me). The level of aggressiveness of prostate cancer is graded on the so-called Gleason scale, where two figures (primary and secondary) are added together to provide a total. Each of those figures is between 3 and 5, so a Gleason score can range from 6 to 10. (Mine was 4 + 5 = 9).
I had an MRI scan the day after I was called in to be told that cancer had been discovered, with a CT scan two days later. (The CT scan was one where they inject the patient with a radioactive substance, and then tell him to go away for a few hours, before carrying out the scan).
If the scans show that the cancer hasn't spread beyond the prostate, a patient is given the choice between having the prostate removed or undergoing several months of chemotherapy. (There are advantages and disadvantages to both). The removal op is, in this area at least, carried out by a robot and involves just a one night stay in hospital.
[NB: The preceding paragraph refers to a patient like me, with a high Gleason score. As Sqad indicates, someone with a lower Gleason score might simply be offered medication].
If the cancer has been found to have spread beyond the prostate itself, then removal of the prostate ceases to be an option at that point. In my case there was found to be some spread of the cancer to my lymph nodes and bones, so it was then a case of "let's throw everything at it that we've got", That meant that I was quickly started on hormone therapy (which I'm on for the rest of my life), with 10 maximum-dose courses of chemotherapy (at 3-weekly intervals) commencing shortly afterwards. Following that I was given 37 radiotherapy treatments, requiring me to attend the hospital every weekday for seven and a half weeks.
At the moment everything appears to be going well in my case, with my recent check-up showing a PSA level of just 0.46 and with no further checks required for the next six months. So even having a high Gleason score, with spread of the cancer beyond the prostate, clearly isn't an immediate death sentence!
You have expressed concern with regard to your father's ability to work after a possible prostate removal op. Page 18 of this document might provide some guidance in that respect:
https://www.uhb.nhs.uk/Downloads/pdf/PiLaparoscopicRadicalProstatectomy.pdf
The side effects of any potential chemotherapy vary greatly between patients. However tiredness is almost inevitable (especially at higher doses). Such tiredness tends to be cumulative, so that it's hardly noticeable after the first chemo session but almost totally overpowering after the final one. (It can also last for many months afterwards). So that's also something that needs to be taken into account when thinking about your father's ability to work. (Radiotherapy can lead to a lot of tiredness too).
That's all that comes to mind at the moment but, if you require any further information from someone who's been on the receiving end of prostate cancer treatment, please don't hesitate to ask me.