See the answers :
Quest1: Can I scan the document and email them? If I need to post which post/courier can I use and how much does that cost?
Ans : YES, a scanned copy works.
Quest2:What all documents do I need to send along with the invitation letter?I got the invitation letter from the International Student Office - but it just says that I am in good academic standing and does not mention about invitation for graduation ceremony. Quest3: Is this ok?
- You must have some official document indicating the date /function /ceremony details about the event. ( Brochure, event flyrer, official notice etc will do)
Quest4: If because of some reason my parents and sister are not able to come to US for the grad ceremony...will it affect their or my future VISA approval requests?
NO, it wont..