I don’t know if this will help you at all, but Pentecostalism comes out of the Methodist tradition, which in turn comes out of the Anglican tradition.
If I were to guess, I would say that they have no history of “bible alone” or “faith alone” - if they do use these ideas, they are borrowing them from outside their own tradition - but “mix and match” religion is quite common nowadays, especially in traditions that don’t have any kind of centralized teaching authority - which means that your mileage will definitely vary - he may or may not hold to one or both of these concepts - in any case, don’t assume that he does because there is nothing in the history of this tradition that would put it there.
There are a variety of different kinds of Pentecostals, including Oneness Pentecostals, who do not believe in the Trinity.
One thing they all have in common is their belief that true believers are identified by their ability to speak “in tongues,” which is a kind of holy babbling.
St. Paul makes reference to this phenomenon in one of his letters; I’m not remembering off hand which one, but if you do a search on “tongues” in the letters of Paul using an on-line concordance, you’ll find it - he didn’t forbid the practice, but he did consider it the least important of the gifts. There is no evidence in Scripture that he himself had or ever used this gift.
PS: their particular “hobby horse” is the Holy Spirit, so one excellent thing to do while preparing to meet this person would be to read everything you can find in the Catechism and in the Bible about the Holy Spirit, and also track down and at least skim through any documents that are referenced in the footnotes, so that you have an idea of the Church’s teaching on this important Person of the Holy Trinity.