You can download VZW Tones from the VZW Today web page from your Blackberry Browser (that should have been your default homepage unless you changed it). Can't remember the URL, but if you don't have it just reply and someone will provide it to you. From the VZW Today page, click on Get Apps. There you will find VZW Tones and other commonly installed apps that you can download.
BTW, BB phones don't have Get It Now because a BB is not a BREW phone. Apps can also be found using Blackberry App World.
It's a good idea to have a media card to backup your personal information like photos and MP3 music. I don't think, however, that tones purchased from VZW can be transferred to your SD card. Certainly it may look like the tones are on the media, but due to license restrictions, VZW only allows the tone to be played on the phone that purchased it -- or, you can download one high quality copy to your computer from www.verizonwireless.com/mediastore.
If your Curve was replaced at no cost to you under warranty and you are replacing tones that your had purchased on your previous Curve, you are entitled to get a credit for those tones. I don't think the Media Center in My Verizon will allow you to re-download any tones at no charge for a BB phone. Better to call Customer Care and ask them how whether you can download them again and they will follow-up and credit your purchases, or they can just go back through your download history (if purchased within last 90 days) and credit them.