You should get a lot out of the journey and experience of moving towards a PhD. Not just 4 years of struggle with then finally a reward. Of course, there will be struggles during a PhD and at the end it is not uncommon to start hating your PhD and being relieved it is done. But before you start doing a PhD, for sure you should look forward to doing the research.

And it is both the research itself, as well as being in an academic environment with all the social aspects that come with it, that should be appealing to you now. I don't know if a fine arts (but you say that's not going to be your field) PhD will be very different from the environment I am used to in fundamental sciences. I guess it can be quite different, more office work and more independence rather than a tightly knitted lab environment.

You shouldn't feel that stressed about opportunities opening up. Or maybe you mean stress in a positive way? Because you also say you are excited. The 'higher calling' thing, you should think a bit more about. It is easy to romanticize a PhD or the work of a scientist.

You should get kids during your PhD, if you can. That's what I hope to do. I will finish my MSc at 36. Start PhD, finish at 39ish. I told my fellow students I can envision myself getting a PhD, getting kids, and becoming a houseman to support my brilliant wife going for full academic career professorship. They laughed hard. And they don't know about my struggles. I hope they found it ridiculous because they cannot see me backing away from academics to take care of my kids. Not that they don't see me not being single.

Good luck!