The cap is only available in light colors. I purchase light brown and painted it dark brown to match trim. It looked great at first. Unfortunately, morning sun has caused it to warp and shrink after two years it looks terrible. Not sure if light colors.hold up any better but I do not recommend this product.
1 inch coated deck screws work great.
You could use two of the 1-1/2 base on the vertical 4x4s or one of the 3-1/2 on each. The top board that isn’t flush with the rest will be a problem. You are creating a frame for the screen so all four corners and sides need to be aligned in a single plane. You will need to add a board across the top that is inline with the sides and bottom rail. Then you can attach the upper base strip to that.
I have never installed this system on vinyl. I would be afraid the screws would not hold The cost of rails is not worth trying to use this product and failing to get the results you want You could contact the manufacturer, but it is doubtful they would recommend it.
Steve, thanks for the inquiry. We do not sell corner pieces for our original Screen Tight product.
Use 1/2 to 1 inch screws. Coated screws are best to prevent rust.
Ours did not come with fasteners.
Yes thin tacks will nail through the base strip. It is flexible, not brittle.
The caps are available in White, beige, grey and brown. When the cap is installed it covers the base completely.
I have never painted any screen tight,but they do make a paint for vinyl siding. I am not sure it will work in this application. Your paint store can help you.