Virtual assistant with Spanish

We are a company based in Spain. We are looking for an experienced Virtual Assistant who can write perfect Spanish and English to work part time (20 hours per week).
We need someone who is reliable, is able to follow precise instructions and pays attention to detail (this is very important).
Some of the tasks will involve answering emails, doing online research, posting in Facebook, Pinterest, Google Plus..., contact forums and groups related to our niche, some Wordpress editing... The ability to create Facebook ads would be an advantage.
This will be a long term job for the right person.