Treat it as you would a semi-formal email. Do NOT use "Internet speak" like "i hv a question and i hope u can answer it." I'm sure that wasn't your plan anyway.
You don't need formal additions, but you do need to observe courtesy.
I have a few questions regarding ... and would greatly appreciate your help in obtaining answers.
1) Question 1
2) Question 2
If you need me to provide any additional information, please let me know. I appreciate your time in responding and look forward to hearing from you.