Only accepted and presented papers will appear in the proceedings if they have been uploaded before the deadlines.
The conference proceedings will be submitted to IEEE Xplore® which ensures a wide dissemination of your valuable work. Once accepted and published (which is usually true for this conference), other indexing services evaluate conferences and independently determine what they will index.
The copyrights of the papers are transferred to IEEE (except if it's entirely the work employees of the US or a crown government).
Authors are expected to attend the conference in person to present their papers and share their ideas. If a paper is included in the proceedings distributed on site and is later identified as a non-presented paper, it will still be included in the proceedings delivered to IEEE. However, it will be flagged as "no-show" so that the paper will be archived but will not be indexed or appear in IEEE Xplore. But: Copyright of non-presented papers is still retained by IEEE.