Hello everyone!

     Long time follower first-time poster here. The next project that we want to accomplish is to screen in our porch that has an existing cement foundation and roof. The goal is a simple frame support with a 24in knee wall on three sides with a screen door. The rough size is 11′ x 10 ‘. I am a fair handyman and have no problem with the general construction of the framing required for this job.  I also intend to put a Screen Tight screen system outside of the framing for ease of replacing the screen in the event that it becomes damaged.
    The only thing that I cant find examples on the internet is the best way to connect the 6 x 6 onto the exterior wall that is currently sheathed with vinyl siding. Also, the roof support that is covered in vinyl, and flashing what is the best practice for attaching the framing to the roof support? Also, the two pillars that support the roof structure what is the best practice to attach the screen framing directly to the existing pillar or should I replace it with the same size 6 x 6 material I plan on attaching to the side of the house?
     On a previous home project, I ordered the wrong size storm door for the front (Lowes special order, couldn’t return) door of my home and neglected to measure twice so I am repurposing that door for this project.  Pictures with text box questions are attached for your expert consideration.
    I was thinking of going with pressure-treated framing lumber, picking the best that I can find, and pre-painting it before the screen frame goes up. I have seen some aluminum framing but don’t think it would look that great for my home. I was also kicking around the idea of using engineered material for rot resistance and ease of maintenance. If you have any suggestions I am open to hearing them. Thanks in advance for the guidance.