I have been working on the issues stated by you. In order to set spaces between bullets and paragraph, please use following code snippet.
para.Indent = 30
In order to set the hanging effect on bullet, you may use margins to achieve the goal. However, for setting "Special" property in Aspose.Slides, "ParagraphEx.HangingPunctuation" is used. Unfortunately, at the moment the property does seem to take effect of set values in PowerPoint. An issue with ID 28415 has been created in our issue tracking system to investigate and resolve the issue. At the moment, you can use ParagraphE.LeftMargin value for indentation.
para.MarginLeft = 100
Thanks and Regards,