Do Biblical Unitarians believe that Christians can pray to Jesus and, if so, that he can answer a prayer in which he is asked about his divinity? I personally believe that there are biblical grounds for praying to Jesus (e.g. this and this), and, as far as I'm aware, many Christians believe the same. However, I'm currently in ignorance with regards to the Biblical Unitarian position on the subject.
I have four questions:

Do Biblical Unitarians believe that praying to Jesus is a legitimate, scriptural practice?
If the answer to the previous question is yes: do they also believe that Jesus can answer questions verbally (as in Acts 9:10-16 and 2 Cor 12:8-9)?
If the answer to the previous question is yes: do they believe then that if one prays to Jesus and asks him if he is God, he will respond with an unambiguous answer?
If the answer to the previous question is yes: has a Biblical Unitarian ever done this?
Biblical Unitarians have a wide range of views about a wide range of subjects - the term simply groups together people who believe God is the Father, not Jesus, and also hold that the Bible has authority in a strong sense (as opposed to other forms of Unitarianism which view the Bible as having authority in a weaker sense). Biblical Unitarians are a faction within Christianity, not a specific denomination.
Question 1. is highly relevant to the defining features of Biblical Unitarianism. If Jesus is not God, is it OK to pray to him?
The answer commonly seems to be yes, but there is debate.
The article Can We &quot;Pray&quot; to Jesus Christ? from BiblicalUnitarian.com addresses this question.

&quot;There is a controversy among Christians who believe that Jesus is not
God but the Son of God, about whether or not we can pray to Jesus. The
only definitive place to go for an answer to that question is the Word
of God. [...] We believe that the Bible makes it clear that one can
pray to Jesus, but does not have to, and we will do our best to show
why that is.&quot;

This is perhaps similar to the debate between Protestants and Catholics about whether praying 'to' Saints is OK. Different people have different views.
In particular, Jesus seems to say we can ask Him for things. John 14:14

&quot;You may ask me for anything in my name, and I will do it.&quot;

However, there is debate about whether this means addressing the prayer to Jesus, or addressing the prayer to God in Jesus' name, which Jesus unambiguously says we can do.
So the answer to 1. is 'yes' for at least some Biblical Unitarians. Even there, though, the emphasis is perhaps different from standard Trinitarian practise.

&quot;Those who enthusiastically embrace the idea of praying to the Lord
Jesus must recognize that this practice ought not to be carried out to
the point of distracting one from the worship of the Father. We are
sure that the Lord Jesus would find it ironic indeed if he himself
were to become the principal object of Christian worship and
adoration, when his entire life and ministry was devoted to the
glorification of his Father.&quot;

For question 2., as the OP points out, there are instances in scripture where people seem to 'hear' Jesus. Since that's the case, I don't see why Biblical Unitarians would object to this idea.
Question 3. moves away from something specific to Biblical Unitarianism, presumably a prayer could be answered unambiguously.
Question 4. is an empirical question, but really two questions. Has someone had an experience like this? Were they having a veridical experience? I'm sure a Biblical Unitarian has done this, but I don't have a link to reports of this.