Thank you for the nice comments! I have already experienced some of the problems you mention; I've learned to do everything offline in a text editor and then cut & paste into the blog, thus having a backup in case there's a posting problem.
I chose the black simply because, of all the templates available, it seemed the least distracting from the content. As time goes on, I'll explore various modifications to the look and feel; I'm the kind of person who just can't help fiddling with things. Thanks so much for your offer of help; you'll probably hear from me soon!