There is the noun "ein Paar", which means two associated humans or objects (das glückliche Paar = the happy couple, die Paar Schuhe = the pair of shoes)
and there is the pronoun "paar" which means some or few and which is often combined as a fixed expression as "ein paar".
alle paar Wochen = every few weeks
ein paar Menschen = some people
So the meaning determines to capitalization:
Ich habe ein paar Schuhe = I have a few (pairs of) shoes
Ich habe ein Paar Schuhe = I have one pair of shoes
In regard of your question: "Ein paar Fragen" refers to few/some questions as questions are usually not handled in pairs. In questionnaires and games that's sometimes the case and - as @hajef pointed out - in that specific case, "ein Paar Fragen" would be correct, thought one usually would say "ein Fragenpaar".
I actually never heard someone use ein Paar Fragen in the meaning of one pair of questions or "Fragenpaar". I think, it's more common to use "zwei zusammengehörende Fragen" (= two related questions)