I was talking briefly with my pastor and didn't get to get into it much with him, but he told me that he was "licensed" to preach. I thought you called this a "faculty" or something like that. Are there various licenses that Catholic priests have; how does it compare to what a deacon (or lay person) can do at Mass? Do they have limits to their preaching? Like a Class D drivers license that lets them preach to bigger crowds?
Preaching as part of the mass liturgy
Canon Law Made Easy website article Who May Preach? subsumes preaching in the context of mass homily under the "office of preaching" which is part of Book III: The Teaching Function of the Church (747-755).
The "license" that your priest claims to have, seems to refer to his office as an authorized teacher of the church. And he obtains this "faculty" by being a "cleric" through the sacrament of ordination.
By canon law he is required to provide one at all Sunday masses and at all holy days of obligation (unless he cannot speak because of laryngitis or other considerations). Canon law 767.1 also reserves this liturgical homily to a priest or a deacon, but not necessarily the presiding priest (in the case that there is a visiting missionary priest, for example).
The article also separates this liturgical homily from other types of preaching, such as during a retreat, where a lay Catholic is permitted to do it (Canon 766).
The article also points out that "mundane", non-spiritual topics (such as calling for volunteer or for fund raising) do not constitute preaching, so if the homily is exclusively filled with these topics (not addressing the readings of the day), the priest has not fulfilled his obligation.
Are there various licenses that Catholic priests have; how does it compare to what a deacon (or lay person) can do at Mass?
The most important other "license" is certainly being able to consecrate bread and wine to become the body and blood of Jesus Christ, a faculty denied even to a deacon. I believe other "license" / "faculty" would be derived from those granted at the sacrament of ordination.
Preaching in other contexts
Do they have limits to their preaching? Like a Class D drivers license that lets them preach to bigger crowds?
In the liturgical context, the limit is having to provide reflection from the readings of the day. I would think there is no limit to the "bigger crowd" when the mass is celebrated in a stadium filled with 10,000s people such as in a youth rally event.
But in a non liturgical context, is there a limit as to the occasion, venue, or crowd size? "Bigger crowd" here can be audience of a book, an Internet ministry such as Bishop Barron's Word on Fire, or a university / online classroom such as the Aquinas 101 course. Do priests have "license" to "preach" in those settings and what are the limits?
I would think the limit is consistency with what the Magisterium teaches, IF the purpose is to explicate what the Catholic church teaches. I would think a priest obtains the authority to teach as assistant to a bishop who in turn is a successor of an apostle (see catholic.com magazine article Authority to Teach). But if the topic is theological speculation, Biblical research, writing a non-authorized commentary, etc. the audience should have been sufficiently informed that he is not teaching a church doctrine. So he can certainly do that and would not be classified formally as "preaching".
How about other kind of preaching "license"? I think a nihil obstat stamp of approval by a Bishop, certifying that there is nothing heretical in a book written by a priest or a Catholic scholar can count as an indirect license. I think apart from being declared Doctor of the Church granted posthumously I'm not sure whether there is another class of license that Vatican gives to a priest/deacon or even a non-ordained Catholic theologian. I still need to research this.
Can this preaching "license" be revoked from a priest? It would seem so, from the case of Hans Küng who Wikipedia says "was stripped of his license to teach as a Catholic theologian" (see the 1979 Vatican declaration).
What is the license that Catholic priests have to preach?
Priests and deacons may preach homilies at mass by the virtue imposed upon them at their ordination. For that much we are sure.
When your priest friend said “he was "licensed" to preach”, probably refers to the fact that he has obtained a Licentiate. Licentiate s would be necessary in order to preach retreats to seminary students in Catholic seminaries, as these retreats are part of their priestly formation.
An ecclesiastical degree in theology, Sacred Scripture, philosophy, canon law, or another sacred science. It ranks above a bachelor's degree and below a doctor's degree.
To be able to freely teach and preach within Catholic institutions of higher education would need to have a Licentiate to perform such duties properly.
The 1983 Code of Canon Law, like the 1917 Code before it, is clear on this point: The homily is reserved to a priest or deacon, as the homily forms an integral part of the liturgy, closely connected as it is to the proclamation of the Gospel, which is also reserved to an ordained cleric within the context of the Mass. The reservation of the homily to an ordained cleric has been the church’s practice both before and after the Second Vatican Council.
Lay teachers would have to obtain a Licentiate if teaching certain classes at such schools, but would not be allowed to preach at mass or give retreats as these are reserved for ordained Catholic ministers and are done so by virtue of their ordination in union with their level of expertise.
The Licentiate of Sacred Theology (STL) with specialization in Sacramental Theology is a research degree which trains students to teach a wide variety of courses, from adult education to graduate courses. The STL also prepares graduates for scholarly research in the field of sacramental and liturgical theology as well as for teaching in Catholic seminaries, universities, and colleges. Admission to the STL program requires a Bachelor of Sacred Theology (STB), a Master of Divinity (MDiv) or equivalent.
The Licentiate of Sacred Theology with a sacramental specialization is a degree of the Liturgical Institute using core courses of the Pontifical Faculty of Theology and electives from the Liturgical Institute's curriculum. Students also join in the Liturgical Institute's daily worship and social activities. - Licentiate of Sacred Theology
Every diocese has a certain number of priests who have a Licentiate, even though they may be simple pastors. Our Archdiocese always has a few priests studying in Rome in order to obtain their Licentiate from a Pontifical University. Some eventually get groomed as possible episcopal candidates.