1. Criteria for setting priority. How is priority established? Is priority guaranteed by the fact of presenting firstly a document against other document that is potentially incompatible?
As a general rule, priority is established by the rank of the entry in the register of entries (cf. II, 3). The first transcription/inscription has first rank, the second transcription/inscription has second rank, and so on.
According to the Mortgage Act, section 123, the date of the notarial act is taken into account if two (or more) notarial acts are presented for transcription at the Land Registry the same day. If two (or more) notarial acts of the same date are presented at the Land Registry the same day, the rank of the entry in the register of entries is decisive (but these are academic-scholarly cases).
This rule does not apply to notarial acts presented for inscription (mainly mortgages): according to the Mortgage Act, section 81, the inscriptions made the same day (i.e. the notarial acts presented the same day) have the same rank (without distinguishing between the inscriptions of the morning and the evening, section 81 adds).
2. Are there any possibilities of that a document presented later may go ahead or prevail in priority rather than other documents or deeds presented earlier?
In general—the question points towards case-law—the priority ranking as established in the land register, could be influenced by later incidents, depending on the legal solution of the incident. An example, if a mortgage takes second rank and the first rank mortgage is annulled, the second rank mortgage will become the first rank mortgage … because the annulment has retroactive effect.
3. Let’s suppose a document presented firstly that consequently holds priority but is affected by defects or lack of legal requirements. How long would it keep priority against other document presented later?
See previous answer.