Dear Esmerald:
Welcome to EyeonSpain. So good Lord Sugar likes this forum. Very good to hear. EyeonSpain has been active on providing information and guidance to expats for almost 10 years now and it was here where the possibiities for refund of investors in failed off plan projects started, through Keith Rule.
You are not responsible for taxes or insurances of people working for you as self-employed persons. In regards to health and safety, they are also responsible of their own work processes and tools and possible accidents if caused by their own negligence.
Of course , you would be liable if accidents happen connected to bad state of the any part of the house they would ve working at. For this, it is good you have a good insurance.
Kind regards
Maria