Since only the tubes carrying the sperm from the testes is being cut, your balls are still producing testosterone and a vasectomy won't cause any physical change in arousal; unlike when dogs & cats are fixed. Not masturbating or having sex for a few days will still increase horniness; at least in those guys who are younger and/or had a high libido to begin with. Any diminishment will be in the first few days afterwards as you likely won't feel like having sex till things completely heal and any change later on I think can only be due to psychological factors or the doctor screwing something up.
Wet dreams in my experience are based on other factors and will have nothing to do with a vasectomy either. For me, I haven't had one since I discovered masturbation and long before I was snipped, regardless of how aroused I was either before going to bed or while sleeping. So if you are still having them despite regularly jerking, I see no reason why they won't continue.
The only immediate difference afterwards was when I started coming again. The first few times there wasn't much volume and it ran out like a facet rather then any squirts and was somewhat uncomfortable. But after the first few times, everything was back to normal and I noticed zero difference in volume, appearance and shooting ability or arousal levels. Any changes over the years in all those areas I contribute to aging and other incidental factors and not the vasectomy.
Like others have mentioned, what it did have a profound effect on was my piece of mind. It felt liberating in a way to know there was no risk of unintended pregnancy and my wife no longer had to risk her health by relying on the pill and if anything, it made sex more frequent

. It also was an asset years later when we were in the Lifestyle since I knew there was no chance of getting anyone else pregnant as well; even if a lot of the ladies I had sex with were older and postmenopausal.