Sometimes, the order of names is alphabetical. Also, if you collaborate with others inside or outside your group keep very clear records of who generated what data. If there are several supervisors, the contract must state the responsibilities of each supervisor.
Will the professor provide equipment and materials? Many projects suffer unanticipated delays.
In engineering and natural sciences, co-authorship is common, but practices vary by discipline. Occasionally, for various reasons--not always the advisor's fault--students do not finish theses and dissertations.
Reviewer can usually relatively easy to identify such parts, for example the obvious difference in language style from other text. How were conflicts resolved? The thesis work should be a training in identifying a specific problem within the field of the study, analysis and the treatment of these in a scientific manner, as well as being able to produce a written scientific thesis about the selected topic.
After approval of the official assignments advisor proposes thesis opponents. Are deliverables promised? Since Sam was experienced and his side-project was promising, it is likely that they could have come to an agreement if they had a live conversation.
Ask a potential advisor for names and e-mail addresses of former students, whom you can contact.