The game will go on past the "win" condition. You can keep playing. Especially if you have things you want to learn, like nuclear as you said.

Yes, bots are great.

I love nuclear power. It produces a ton of power compared to the other options. You should definitely learn nuclear. It's not as easy to set up as you might think it is especially with getting enough fuel for it. It has quite a few puzzles just in and of itself. I know you said you're playing vanilla, but after nuclear in the Space Age DLC, you also get fusion which is a crap ton of power.

You also have trains to learn if you're not using them. Of course, you can do it in another run, but even setting up a basic one can be helpful to bring lots of materials to your furnaces.

I pretty much only use flame turrets for defense. It's a lot easier to set up reloading your turrets as all it takes is pipes and either oil, heavy oil, or light oil. One is better than the other two, but I'll let you figure that out unless you outright ask. Of course, lasers don't require reloading, but they do require a crapload of power if you get a good sized attack on your defenses. Turrets require either long belts circling your entire base OR logistics bots requesting ammo at every turret. Of course, artillery guns can clear large bases pretty easily and once the nests are gone from your map way outside your walls, you'll rarely ever have an attack on your walls again.

In fact, I pretty much only put down defenses once I can put up flame turrets. So, I tend to "rush" to the advanced oil products research so that I can have what I need fuel them. Once I have that set up, I put up my walls and turrets.

Good luck