Who knows? When the next version of ZC comes out, it may have some new,
can't-live-without features that you'll want. And any changes you made to the
core files (classic template, included) will be over-written and you'll have to start
alllllllll over.

What did you put in your custom template file? The css folder/files from classic? The images folder/files? The template_info.php file? If ZC isn't reading your
chosen template, you should have at least be seeing the default css (lots of
different colors) from template_default.

Are you making your file changes on the server? You should be making your
changes on your computer with a simple text editor, then uploading them to
your server.

If you want the tagline gone, and don't plan to have your own text there...find this in your stylesheet at around line 209:

#tagline {
color:#000000;
font-size: 2em;
text-align : center;
vertical-align: middle;
}

and change it to this:

#tagline {display:none;}