No idea if they will fit or not. Not sure if companies use standard side mount positions.
One piece of advice I can give you though is don't rush and buy seats just cos you can afford them now. I spent ages deciding on my old cobras. Every car, especially clios I saw with the monacos in I hated. They look terrible and chunky and really boy racerish. Plus I believe they are steel frame, so heavy and not very comfortable.
To get a really nice look you need to be looking at a much more expensive seat. I had the cobra imola pro in carbon. They are about 600 a seat but they actually suited the car as well as being super lightweight and when combined with the 3 inch sabelt harnesses u didn't move at all no matter how hard you drove.
Subframe u don't need in theory, but I would seriously recommend having the mounts welded to the chassis by a Motorsport technician and not just an everyday welder. They will know what works and doesn't.
To give you some idea, seats, mounts, sliders, 3 inch 4 point harnesses came to about 2k. But it was the best thing I did to that 172