Assignment of a Resource to multiple activities at the same time. (& understanding planning process)

hi,
I have read most ot the planning and resource allocation/assignments posts i could fine. Still I do not understand how the planning process works and how it it influenced totally yet but I do realize that fundamentally Projeqor assumes one resources can only work on, or can be assigned to one activities at a time.

However, in our environment it is difficult to dedicate on resource to one project activities at a time, they have other operational demands and do not work on projects that are not manged by Projecqor.

Is it possible to assign one resource to multiple activities that run at the same time and then to get the planning engine to honor this?
What is the simplest metode to make sure an activities starts on n particular date?
Other than the online manual, where can i learn more about the planning mode descriptions to understand exactly how I can use each of them. The descriptions do not help me understand how i can apply them so that the planning process behaves more like i require.

Thank you
Lombard

thank you for your quick response

"""Is it possible to assign one resource to multiple activities that run at the same time and then to get the planning engine to honor this?
YES !!! """

Can you please share some tips as to how this could be done, which are the best planning modes to use for this situation. What are the other key configurations to consider.

Unfortunately I will not be able to raise funds for Training until i can demonstrate that we can actually use the product, something i am trying to do by using it for a new big project we have started, but i need more information or help with how the planning engine works so that we can understand the expected outputs of the planning process and how we can adjusted to meet our needs. How can you please help kick start me on this journey. thank you.