This error is caused by the fact, that you are using PHP lower than 5.3. In plugin version 0.2 I used some code structures introduced in PHP 5.3 so older PHP versions simply don't understand the code. But I realised, that most virtual servers still have PHP 5.2 as a default version, so I'm going to give up all the benefits of PHP 5.3 and make it more compatibilile. Please try to install the next version which should appear tomorrow or the day after.
About the screenshots: I have uploaded some images but they did not appeared on the plugin page. Now I'm trying to figure out, why this is so.
It's possibile to set position of watermark. Please, see the FAQ section.
Thanx for your suggestion, I will implement that. For now this plugin adds watermark only to fullsize images, but I'm creating it for my own and the current version doesn't satisfy me at all, so you can be pretty sure that it'll become a powerful tool after few upgrades.