The second floor porch has two areas that need to be addressed: flooring surface and railing.
The flooring surface has deteriated to the point of being borderline waterproof. Patching will buy some time, but only so much. Several areas of the flooring surface have a spongy feel that could indicate that the sub-floor has already begun deteriating. The most practical time to replace the surface will be when siding is replaced on the East and South sides. This will allow for proper flashing where the wall meets the flooring.
The railing has several areas that need attention. Many spindles are broken/damaged and need to be replaced. Several top and bottom rails have signs of rot and require paint at a minimum. Wooden posts need attention to ensure that they are structually sound. The hieght of the railing may need to be raised to meet building codes. Metal or composite railing materials will be considered in place of the current wooden components.
These two projects are best tackled at the same time. While the flooring is being addressed, posts can be examined to ensure they are structually sound. If railing replacement is warrented, installing the new components will be easiest and most robust when done concurrently with the flooring.