I would consider myself a scientific researcher because I systematically observe people and behavior and/or because I conduct experiments. Whether I do this alone or with a group wouldn't influence this, but it may change how much I enjoy it.
Depends on the type of work or topic. In other words,
1. If you are a lead and have appropriate skills then the redundant and refinement work is best suited for your sub-ordinates (students working under you). This is especially suited when the time is short and more different field of study is needed.
2. If you are a part of a group then you have a part of the whole work to research on.
3. And the best, when you are not in a group and the time is not short and the doesn't require bunch of study, then you are actually researching and concluding or in some ways searching something new.
In point 1, you will control, direct and conclude the work and its result.
In point 2, you will be doing the allotted work.
Point 3, is like the kind of work done by Albert Einstein, Newton, and many more. In all case, you can feel that you are a scientific researcher provided that you are honest, curious and punctual yo your research.
Sir, if you were asking the above question in a personal way then my answer would be just a word long I.e., "YES". Very precise.
Depends on situation. Some routine work such as - in my case extraction of DNA or measuring of basal soil respiration can be done by students . If you want to show some new advances or new methods then it is better work together with students. Third, if you start something new then is better do it by yourself to avoid some errors etc.