I don't have a Storm, but you should have a link to the Verizon homepage in your browser bookmarks. From there you should be able to download apps, etc.
I don't think you can download from VCAST on a BlackBerry, but I might be wrong in that. There is no need to pay for ringtones when you can download them free from some websites and you can create your own ringtones on your PC, which many here do, and copy them to your device.
Here are some places to download ringtones from your device. Where Can I Download Ringtones? - BlackBerryFAQ
I especially like tuneusin.com.