Hosting GPL themes, licensing, links to my blog, themefores

Exactly what is and what isn’t acceptable is determined by the Theme Review Guidelines and the theme review team. New themes that are derived from pre-existing themes tend to be judged on a case-by-case basis.

The article on your blog is a good idea. In fact, theme developers are encouraged to provide a url (via the Theme Url tag) on one of their own sites where potential users can look for supplemental information, faqs and possibly even support for your theme.

If in doubt, you can always ask the theme review team directly before you submit your theme via http://make.wordpress.org/themes/about/how-to-join-wptrt/ Also check your theme against http://codex.wordpress.org/Theme_Review and using http://wordpress.org/extend/plugins/theme-check/

Good luck 🙂

That means don’t ALSO post the same theme on a non-GPL place or elsewhere with a NON-GPL license.

This is one of the less-fun parts of the Theme Review process. Given WPORG policy, we do check Theme URI and Author URI, and will not allow Theme submissions from developers who distribute or promote non-GPL-compliant Themes on Theme URI or Author URI.

Themeforest is a bit of a gray area in this respect, but the current stance is that promotion of Themeforest Themes falls on the wrong side of this requirement.

I will definitely write in the description the original theme name and a link to it! Also what have been modified and what I have used directly from their theme.

This is all fine, but doesn’t technically meet the requirements for proper copyright notice/license declaration. The proper place for this notice/declaration is in an appropriate file header in the package, which for WordPress Themes is generally accepted to be the style.css file. Per GNU, proper copyright notice/license declaration looks something like the following:

Awesome Derivative WordPress Theme, Copyright 2012 Petarg

This program is free software: you can redistribute it and/or modify     it under the terms of the GNU General Public License as published by     the Free Software Foundation, either version 3 of the License, or     (at your option) any later version.

This program is distributed in the hope that it will be useful,     but WITHOUT ANY WARRANTY; without even the implied warranty of     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License     along with this program.  If not, see <http://www.gnu.org/licenses/>.

For a derivative Theme, you should include the original copyright attribution. For example, replace the first line:

Awesome Derivative WordPress Theme, Copyright 2012 Petarg

…with something like this:

Awesome Derivative WordPress Theme, Copyright 2012 Petarg

Awesome Derivative WordPress Theme is derived from Parent Theme, Copyright 2010 Parent Theme Developer, and is released under the terms of the GNU GPL, Version 2.0.

Just a note: while attribution is desirable and admirable, all public-facing links must be your own.

Listen to Chip but as I understand it…
1. Yes
2. You can only promote GPL themes on the pages that you use for the Theme Url and Author Url in your submitted theme

Case One:
2. No
3. Yes

Case two:
4. Not sure. I think Woothemes are GPL but check with the theme-review team for the definitive answer on this.
5. Yes