1) For the Nursing position: You could use the Repeated option to get more timeframes, using the first for the FT hours and the second for the PT hours, with the total for each completed to date in the Total Hours slot. Then at the end of the narrative state that your (I presume, indefinite) plan to return to full time work in X-Y months.
2) For the Data Coordinator position: Give a brief overview of the study. State your role. Discuss impact, if any. If you are aware of the hypothesis and study design, you could reasonably list this under Research, especially if you could hold up to intensive grilling on the methods (which happens at interviews sometimes). If you don't have an idea of the broader picture, you should probably list it as Employment-Not Medical/Clinical.
Enter your Start Date and the current date (or the earliest date you think the study would be complete) for End Date. In the narrative mention that the exact end date is not yet known.
3) Hopefully, you have more recent Shadowing than that to list, in which case, I'd summarize the long-ago hours briefly ("In addition, I shadowed for 200 more hours in 2004-2006, in a wide variety of medical and surgical specialties"), at the end of the narrative box.