AWS New EC2 Instance and EBS Storage

Our current web application stores files directly on the webserver.  We've thought about migrating to S3, but at this point migrating from a traditional dedicated host to AWS it would lighten the load some to just use their EBS service.  

So my question is, when spinning up a test instance I see that there is a root drive with 8 gigs of space by default.  Can I just up that to 500 gigs and call it good?  Or do I need to add another volume of an EBS and give it the 500 gigs?  If the latter, my web app uploads files to the webserver currently under a /home/domain/public_html/uploads folder.  If I attach a EBS volume vs use root do I need to config somehow so that my web app uploads to a different location or is all that configured?

If I just expand root volume is it also an EBS and is there any problem with doing that?