Softwood summer cut trees/logs can blue stain quickly in high humidity conditions. Bugs will infest logs with bark on them. Debarking will help a lot for bugs but not for blue stain. Winter cut softwood is better for eliminating blue stain.
Storing logs should not be directly on the ground but up on some extra low grade logs called "runners" or "bunks", as you appear to understand.
You should develop a design of the frame. Obtain a stock list of timbers needed. And then harvest your trees to fill you stock list.
Different ages of dryness is a concern but not the end of all procedures as you can cut your joinery to compensate for shrinkage.
Good luck with your project.
Jim Rogers