*** EDITED: Forgot about the overheating question.
As far as I know, I didn't know about that overheating thing to be honest. I haven't searched or something like it, though. And I had the PS4 running for like 12-13h (and even more) without any single "overheat" using it's full capabilities (?) (FFXV), so no. It probably was an isolated case. And you don't need a 4KTV to enjoy the PS4. It's true it has some benefits like the HDR and 4k scalation, but it is too expensive -the tv- to consider it a "must", in my opinion.
If your most notable game with the PS4 will be P5, maybe you should wait and see what benefits you can take of the PRO version (supposing it will have a benefit, of course). If it's something like FFXV that has almost constantly 60FPS support with the option to improve the graphic quality. In my opinion, if you will have a wide variety of games -specially of those who profits the PRO features like FFXV as I said before-, the PRO is your choice. I have seen videos of FFXV running on PS4 Phat and gosh, it was horrible, and even worse if we compare it with the PRO version.
Well, if you can, go for the PRO. You'll be totally satisfied if you're going to play many games and specially games that need a lot of resources (FFXV, Horizon Zero Dawn, and who knows what else) with the chance of boosting those games that doesn't have native PRO support (thanks to a 4.50 firmware option -if it hasn't been removed after the beta-). So, in my opinion (and I have a PS4 Pro), it is totally worth it, and if you could try both Phat/Slim and PRO you'll see what I mean. Look at videos on Youtube, if you are unsecure!
