My Broom Plant

I have this lovely plant outside my front door. I don't know how it got there but I am sure that this is the first time that it has flowered. What I would like to know is what I have to do to it to keep it strong and I would also like to have one in my back garden.

Can I take a cutting.   ?????

Can I use the seeds from it. ?????

Do I have to prune it back.     ?????

Where is the best place to plant it in my back garden which is south facing and gets the sun all day.

I have raised beds in my garden and would love it to go in there as the dogs might pee up it..

Thanks so much if you have got this far in reading my questions. This is my first post on here.

Tracy