The second part of your question is common, but I don't hear the first, 'helpful' part of your sentence very often....
"It would be helpful if you would pass me a pen."
What I say, and hear, are sentences like these:
"Excuse me, could you pass me a pen? Thanks."
"I'm sorry to bother you, but could you pass me a pen? Thanks."
"I'm sorry, but could I bother you for a pen? Thanks."
"I don't mean to bother you, but I need a pen... could you pass me that one? Thank you very much."
"Excuse me, are you using that pen? Could you pass it to me?"
"Excuse me, are you using that pen? No? Then could I borrow it for a minute?"
"Excuse me, could I borrow that pen for a moment?"
"I'm sorry, but I left my pen at home... could you loan me one of yours?"