I can do my best to answer you. Hopefully someone will help me out, but as a seminarian who has a permanent deacon both at my home parish and working at the seminary, I can give you some answers.
A deacon is an ordained clergyman. He can be married before ordination, but once ordained, he cannot marry. (If his wife dies and he has young children to raise, exceptions can be made, but this is not the norm) Deacons have some of the faculties that priests share: they can assist the priest with the mass (such as setting up the altar, purifying the vessels after communion, etc.) as well as preach, they can also preside at weddings, funerals and baptisms (someone correct me if I’m wrong there, I’m pretty sure). Obviously, a deacon may not offer mass or hear confessions.
The training for the diaconate varies from diocese to diocese. In our diocese, the deacons in training go through about four years of theology. Since most of them have families, they usually have a program where they go away for classes about one weekend a month, and read and write assignments in between. In addition, they take practical courses. For example, we have the deacons-in-training come to the seminary one night a week to have an informal class with our Father Rector, who answers their basic questions about liturgy, dealing with difficulties with parishioners, etc.
As a side note, deacons generally do not work full-time in their ministry. Most assist at weekend masses, as well as funerals, marriages, etc. Most have normal day jobs during the week. I know a deacon who is a lawyer as well as a seminary professor, and the deacon at my parish is the property manager at the seminary residence.
So, deacons (at least here in my diocese) do have a good deal of knowledge and experience. Maybe you would like to ask the deacon at your parish about his formation?
Oh, and you asked about qualifications. I think this is pretty standard: Yes, men do get turned away from the diaconate, as it is a calling, not simply a job. Here, men must be at least 35 years old (so as to make a mature decision) and they must have their wife’s consent.
Hope my random assortment of information helps
In Christ and Our Blessed Mother,
Frank