Hello Samuel,
Answer to Question 1:
The prestress on the anchor can be defined by applying a member load of type "Initial Prestress" to the tension member of the anchor.
Answer to Question 2:
When you define an initial prestress, it will act on the undeformed system at the beginning of the analysis. As the system deforms and yields, the prestress force may reduce. If you require a specific prestress force at the final state, you should use the "End Prestress" member load type instead.
To ensure the anchor is connected to the foundation slab, make sure that the end node of the anchor member is integrated into the surface of the foundation slab. Once this is done, both objects will be statically connected.
Answer to Question 4:
The anchor member automatically generates a tension member and a pile member in the background. This automatically generated pile member functions similarly to a manually created pile, including the consideration of the pile tip resistance. If you do not wish to consider the tip pressure, simply set the corresponding values to zero. You can find the relevant settings here:
Answer to Question 5:
Unfortunately, the geometry of the anchor head cannot be defined directly in the program. However, you can model an additional head plate manually for improved load distribution.
Let me know if you need further clarification or assistance! 