1. Background Image - I'm not sure why the background image doesn't appear in your blog. I think the referrence for the image is not in use anymore. But you can put your own image instead. All you need to have is an account such as http://photobucket.com/ where you place your pictures or photos. Then reference to the image address for your background image.
2. Talk Box - There are quite a few services for this. You can try searching around in Googles. But the one Jolene and I are using is cBox - http://cbox.ws/ Just create an account there and there'll be instructions for you on how to paste the codes into your template.

My codes are very different from yours. You can see if Jolene's codes would be any help to you cos you two's blog layout seems rather similar. If not, I think a simple template from blogger.com will actually do just fine too.

Have fun blogging~!