Create new Task with custom form

Hi,

In Tasklist I have a create task option which allows me to create user task without it having to be defined in a process definition. I use taskService.newTask() method to create the task and the use setters for assignee, due date etc., which is great. However, I have few questions regarding the options I did not manage to find:

  1. Is there any way a user can define form fields for tasks created this way?
  2. Could task be assigned multiple users?
  3. In case task is assigned to multiple users, is there any way to define multi-instance tasks with serial execution, meaning the users will get a task one after another?

I would really appreciate any kind of information that would lead to a possible solution.
Many thanks,
Julija