A: There is no time limit on the trial version. But the output PDF, in trial version, will be stamped with a watermark.
A: Yes. You can specify the default source or destination folders. It can be done via menu "Settings > Default Folder".
A: You can change the PDF properties in menu "Settings > PDF File Properties". You can set "Allow Copy", "Allow Edit", "Allow Print" and also the title, subject keywords, etc.