Cost - Basic Xanga is free, and you get a lot for free. If you want more than what basic Xanga costs you can get more image hosting, more profile pics, Xanga skins, no ads and more for just $25 per year.
Parents Permission Policy - As far as I can tell Xanga does not require parents permission to join Xanga and they do not have an age limit to their service. I emailed them for more information but as yet have not heard back from the. This is what I could find.
From Xanga help pages:
Profile Page - The profile page is pretty basic but that can be changed with the right template. From your profile editing page you can edit the look and feel of your Xanga profile page, add skins and change your account settings. Also control your photos, music and videos from your Xanga editing page. Other things like your blog, blogrings, guestbook and chatboard can also be accessed from your Xanga editing page.
Photos - Xanga gives you a photo album where you can post your own photos. Photos can be kept private or made public. Xanga even offers the Xanga uploader to make uploading batches of photos easier. You get 1G of space for your photos. If you need more space than 1G for your photos you can upgrade to Xanga Premium.
Blog - Publish your thoughts and stories online with Xanga's blog. Add photos to your blog too. Tell about your vacations, your son's sports or anything you want.
Advanced Design - You can create your own Xanga skin for your Xanga profile and add it to the skin editor. You can also use the Look & Feel page to add your own colors and backgrounds.
