Question 4 - Budget holders are nervous and using Agile because seemingly the budget is unconstrained. How do you manage this concern?
The prioritisation of requirements at the beginning of the project is key here. Once a budget holder is educated as to how the requirements are identified and prioritised then those concerns are often ameliorated.
The MoSCow approach allows the business to see that the most business critical requirements are delivered first and at a second level of prioritisation, the highest risk features are delivered early. If they highest priority and highest risk features are delivered first then at that stage generally the contingency and resource is available to deliver without impacting the overall project.
That last thing that any business wants to see is high priority features delivered at the end of the project when the budget is getting thin.
Another key approach here to reassure the business is focusing the testing of the platform from a requirements perspective, directly linking the testing of the system to the defined business requirements. It is all well and good providing and running test scripts that focus on the underlying technical configuration, that will prove that the code works, but does it prove that the business requirement has been met?