I put up a log House here in 2002...It's a very difficult undertaking..I can suggest a log home company if you wish..They are very good and will build the shell for you on your foundation.. You will need a General Contractor in addition to the LH people..
http://www.hearthstonehomes.com/
The guy who was my salesman/planner no longer works there. His name was Dennis and very helpful..
...If you have any specific questions, please ask..In the meantime, subscribe to "Log Home Living" which is a mag devoted to log homes..They have a lot of good articles and the advertisements help too
I used the "Square Appalachian" style logs. There is "chinking" between the logs..They used ground up car tires in plastic bags as insulation between the logs and under the chinking.
As for roof insulation, they put 6" styrofoam panels on top of the 2x6 planking..Then they used plywood on top of that, then felt paper and shingles...I swear..The snow never melts off the roof till the sun hits it...No inside air leakage at all
Another thing you will notice is how much more efficient the logs are for heat retention in the winter
Maintenance on a log house is brutal...It's constant, but the effort is well worth it as a well maintained log house is beautiful.
Also, allow for shrinkage in the logs...I have 10' ceilings , and after 5 years, the house shrunk 4" dues to the logs shedding moisture. If you went for 8' ceilings you would wind up with 7'6 ceilings which might be a little low for some.