Answers
Please have in mind that all legitimate spouses can be included in the application for the Greek Golden Visa.
According to the recent change of the L. 4251/2014 (immigration law), a de facto partner can be included in the family members, who can apply for the Greek Golden Visa as dependent applicants. A requirement for this application is a notarial cohabitation agreement to be signed before a Greek Notary and be registered in the books of the competent registry office.
According to the law, family members of third-country citizens entering the country due to Greek Golden visas are spouses (you need to be married and provide a recent certificate of marital status); the other spouse or partner with whom a third-country national has a cohabitation agreement in Greece (you may provide one in your greek golden visa application); the direct unmarried descendants of the spouses who are under the age of 21; the direct unmarried descendants of the supporter or of the other spouse/partner, provided that their custody has been legally entrusted to the sponsor (for his/her children) and to the other partner (for his/her children), under 21 years of age; the direct relatives of the spouses in the ascending line.
Unfortunately no. You must either get married or sign a notarized prenuptial agreement here in Greece.
The unmarried partners of a property investor are not entitled to a residence permit. Family members do not include unmarried partners but as a family member is considered the partner with whom a third-country national has a cohabitation agreement in Greece. The conclusion of a cohabitation agreement in Greece is a very easy and not expensive procedure that takes place in front of a Notary.