Pawel, I found myself in the same situation. If I remember correctly back in 2010 all themes were documented much better. I think there was a pdf file in each archive (if my memory serves me good) and there one could find complete instructions on how to bring a freshly installed Gavick Pro theme in the form of the one Demo'ed on
www.gavick.comI own a site that had a gavick pro theme (one I installed back in 2010). When I switched to Joomla 3.x I found the theme was no longer compatible and since I didn't had a Gavickpro membership anymore and Gavick discontinued the support for that theme I was forced to switch to a different theme provider (also paid).
Recently I decided to switch back to GavickPro as I wasn't satisfied with the theme I currently have on
www.RoundNews.com. I didn't even go to check what themes were being offered because I know GavickPro does a good job on updating old themes and providing new themes. At least this was my feeling. Anyway, I ended up trying at least 4 different themes which I failed configuring with ease.
I think I will stick with gk_news but for now I am searching for documentation on how to configure the main page to look exactly like that of the one from the Demo. I also have to find out where all layout areas from the theme are detailed so that I know how to position the already installed modules. I must admit I forgot my way around a Gavick Pro theme and I would appreciate any help I can get on the forums since now I have a rather big site and everything is harder with a bigger site. I am doing the new template install locally on a mirrored copy of my news site which I have to update at least a couple of times per day with the latest news from my site. I do this because in the end I want to replace everything I have now up on
http://www.roundnews.com with what I have locally.