Just wanted an answer to the question above. From what I'm reading I'm not entirely sure if it makes sense in the setting as in lore it is a very difficult form so I just wanted some input on the matter.
Not a lot of Jedi use it, but some do. The standard practice is to start off with Shii-Cho, and then learn other forms through RP. So if you could find someone to teach it to him, why not?
I would typically be inclined to say no. Although in reality in the RP, Forms aren't overly influential, but personally I enjoy them myself. But to answer your question, I would be inclined to say that Vaapad is beyond the abilities of a Padawan to really learn, but to my knowledge there's no rules against it if you did decide to go that route. That's just my two cents, though.