Check this out, good evening reading. I am most familiar with Fig. 1-3 but have diddled with some of the others. Pay attention to the building sizes and timber used. I suspect if engineered today the timber sizes would be increased some what.
http://www.tfguild.org/joinery/part2.pdf To answer your question in any reasonable sense goes beyond reasonable guise of the forum. And so your education begins.....
As for post sizes 12" x12 " post may be over sized, but I do not have all the facts. I have a 30'x60' clear span, king post building, w/ 16' tall post. They are all hard wood of various species. They are fan tailed posts, meaning they taper from the bottom to the top(see link provided) most are 7x9 at the bottom to 7x12+ at the top. This was built about 10-14 years ago. Today they would all be 9"x 9" at the foot and 9"x14" at the tops. The change is due to learning as you go. It is not a structural issue but more a joinery driven change.
The tie beams are 7"x 9"x 30', there are no joist cut into them. I have lodged joist on top of some for minimal storage in the truss roof system.
Rafters similar size but have 2x's let into the faces for purlins.
Joint for the king to tie connections...... No need for plates. I can't link it but it is found here. Historic American Roof Trusses A extra long through tenon with a wedge on the under side of the tie beam, for a dutch flavor, would be on such connection possibility, pegs in the face as well.
http://tfguild.org/pubpg.html You live in an area where your could easily find an engineer schooled in timber framing to assist in proper sizing of your post and beams. Search the Guild site for a list of engineers.