NO - The programme is open to everyone. You'll also receive specific training before you go.
NO - Unless a basic knowledge is specifically required for the tasks that need to be done. Linguistic support will be available to you during your project, so you'll certainly learn some Spanish while you're there.
YES - But as a participant in the European Voluntary Service, you are entitled to specific free insurance. Ask your sending organisation for details.
If your situation is very difficult and your problems can't be solved, there are ways of terminating your volunteering agreement - as a last resort.
NO - You will not need to pay anything to participate in the European Voluntary Service.
YES - National volunteering schemes are not necessarily open to non citizens. Contact the organising authority to find out.
POSSIBLY - Participating in a volunteering project does not exempt you from following national visa regulations. Make sure you do your research!