Internships limitations & legal aspects

Hello,

I would like to ask help me with clarification of couple of questions related with labour law in Spain. I need this information but it is nearly impossible to find any information on this topic.

I would appreciate any help.

My questions are:

1) How many (paid or un-paid) interns can hire an "empresario individual" or "sociedad de responsibilidad limitada"? Is there any limits related to this issue?

2) Is it possible for an "empresario individual" or "sociedad de responsibilidad limitada" hire a person/get an intern without formal selection process of candidates (for example, hire a friend/relative etc. without posting any job offers beforehand and without any interviews and other formal processes of selection process of candidates)?

3) In case if "empresario individual" or "sociedad de responsibilidad limitada" has stable zero (or very low) profit and big amount of non-paid interns (considering that all taxes are paid), will this situation lead to any legal problems?

4) If we imagine, that a person because of whatever reason is willing to pay a big amount of money to get a job/internship (for example in a very famous company) and this famous company is willing to accept the deal because of severe lack of cash, will in this case occur a break of any Spanish law?

Thank you for your time

Best regards