You can get a background of the software to predict RBS with this research article.
I have tried ELPH which gives a sequence logo and fairly simple in case of finding motifs. I am not sure about RBS prediction using ELPH even though they claim that is it used for RBS prediction.
Yes, the RBS Calculator can be used to predict the translation initiation rate of internal start codons, particularly to minimize undesired expression. Please let me know what improvements we can make to the user interface and we'll do our best.