Can the research proposal be exactly 10 pages?

We do not have an exact prescription in this regard. The point I made was that the shorter and clearer the research proposal the better. The explanation of the background can take two pages and if you can formulate the research problem and central-theoretical argument in one sentence each you are then sure of what you are going to research and the direction in which you are going to solve the problem. Just remember that the reference list accompanying the research proposal should contain all and only the publications you have consulted for the purpose of writing the research proposal. My experience in guiding post-graduate students taught me that a concise well-argued research proposal with clear-cut statements is more beneficial for the study. On the other hand a vague research proposal tends to divert the direction of the researcher and the study-leader often.

Must the presupposition(s) of the research student always agree with that of the study leader?

A good study leader will respect the paradigmatic stance of the researcher if it represents a plausible approach and position. The study must then be guided within those parameters. If the leader does not agree, he/she should not accept the appointment and refer the student to someone else. The student does not have to agree with the supervisor and vice versa. The student should prove that he/she employ a scholarly methodology and that findings are valid within the paradigmatic context.

Is it a requirement to use a colon in titles?

No, it is not. You can use a colon if the title requires it. For example: Violence in South Africa: Politically motivated or a historical heritage?

I wanted to know how a student proceeds if their topic / subject is relatively new and there is limited literary information available?

All research commences somewhere. If you have a valid research question, work with the available material and do empirical research or evaluate oral traditions. In this way you could contribute to the expansion of your field. I would recommend that you state right at the beginning of your research proposal that sources are limited but you intend to take the research further by using empirical methods and oral sources. In the end readers will evaluate your findings to ascertain whether your findings are valid and plausible.