Correct organization of the database structure and selection
First of all: It is necessary to create one table for each task?

In my opinion: No

You can create only one table "Tasks" where you define a name for your Task and define your standard properties of a task. Whenever you want to create more tasks, then you need to create new tables every time.

As an example: If you want to save humans, you don't need to create tables like "female_childs", "males", "females", "died_females" or whatever - Just create one table "persons" where you can store stuff like "gender", "alive", "birthDay", "deathDay"... 

Your Question: Order of execution
In this case, what you need is some sort of sequence to order your tasks. This can be stored in a new table alongside with your device, like that:


DeviceId
TaskId
SequenceNr


I think I've got your confusion about these dynamic task properties but as Basil Bourque describes, you need a "child" property table to store information like you want to do it.

Your third question is now obsolete :)