Answers

Yes, it would be fine, but I would check on the local codes for vapor barriers.

Not a clue on this ”tar paper”. Sorry.

Yes

You will have to cut2” or 2 1/2” Schedule 40 PVC pipe for spacers and then run lag bolts long enough to get into the logs far enough to hold. Be sure to keep the first board on your deck back a little to allow water to run down thru.

Sounds like it needs to be caulked completly on the exterior. Call Mike at 866-670-3020 for help.

The checks are not a concerns unless thay are running into a window or door jamb. They should be filled then on the exterior. Otherwise leave them alone.

I would use Grip Strip backer foam and then use Perma chink to fill. You will need to inspect it a coupl of times per year for failure. The Perma Chink will also take the stain color. Try to use a color of chink to match stain.

You will have to cut that portion of the log out and replace. Then match the stain as best as possible.

I doubt that it is structurally unsound in the walls, thebalcony might be. You should get a structural engineer to look at it. You might try calling Ryan at 877-788-5647 to see if he knows of anybody in your area.

Call Ryan at 877-788-5647 for help.