It looks like a poncirus trifoliata. They make very good plants for under windows to keep would be intruders out,but otherwise they have little use for anything but grafting rootstock for desirable citrus cultivars.
Here's mine
{{gwi:599903}}
seed grown for rootstock for my meiwa kumquat tree. It often grows as a bush.

I don't know. To me it looks more like a citrange or citrumelo or some Trifoliate-citrus hybrid. I don't think Poncirus leaves smell when you break them. But citrange leaves smell like those of an orange.

If it's evergreen, then likely a hybrid like Citrange. Perhaps used as a rootstock?

Are you in zone 9 and is it in a pot or in the ground?