question about buying pro package

Can I add button on the slide and direct to a new url after upgrade to pro? I am running a website in a testing site. If I buy pro version now, after I release the website officially (with a new domain) , can I still use the pro version robo gallery?Is the $30 dollar for pro just pay once and lasted for future? I cannot find the way to make slider mobile responsive. How can I make slider mobile and tablet responsive? What is the max no. of slide I can put on the slider? Can I add text ad text amination directly on slider after going to pro? Thank you.