Are the tasks representing the same activity? If they are, then you can just extend the design of the task process to include the additional stages of activity required. If you want three distinct tasks, it becomes somewhat more difficult as you need to design the main process with some business rules that understand whether the path you are heading down requires 1,2, or 3 tasks.
Usually if you want to have a process with sequential tasks, you need to have a status between each one to allow the main process to 'rest' whilst waiting for the current task to complete. You are then able to automatically kick off the next tasks once the first one has been completed by using pre-conditions after each status that check to see if all current tasks are complete.
Hope that give you some ideas, but please give us more information about some of the use cases that you're considering?
Thanks for your reply , Andy. This process is still in the sage of "incubation" by the user - he has not fully thought out his requirements yet. However, I asked him your question and he said that there would be at least one of the tasks (the last one) that would execute or not based on the outcome of another previous task. Would it be possible to create a condition that checked for the outcome that he wants? For instance can you base a condition on the results of a query?
There are some ways of testing for various outcomesof previous tasks, but the more options that you want to cover, the more complex the process will become in order to reflect the rules that are being put in place. In essence, the use of well thought out conditions placed on pre-conditions will do a great number of things, but in reality, until you have defined the desired process, it's not that easy to give you a hard and fast approach that will fit all.
As far as queries go, you do have the ability to relate process actions to query results through the bulk actions mechanism, however, this is query-centric rather than process-centric, so you need to run the query in order to initiate the bulk actions. Having said that, there is a scheduler linked to the bulk actions and this will run in the background to execute defined queries and their related actions.