Hi, we are remodeling our kitchen...our house ranges from 160 years of age to 40....lots of additions... Anyway, we have our kitchen walls all open and down to the Log Walls(?)...they are laid in long with 2 posts in the middle-ish. The chinking is non-existent and there is some horse hair insulation stuffed in the cracks. There is no insulation and no vapor barrier...should we:
1. Fill the spaces between the logs with expanding foam insulation (e.g. Great Stuff)?

2. Can the tuff-r foam insulation be used as a vapor barrier? Or should we get some tyvek or similar to use as a vapor barrier first? We do plan to re-side the house at some point with the intent to wrap and insulate...but it may be a few years depending on how far this kitchen remodel goes over budget...

3. Does the tuff-R foam insulation really have an R value of 15 at 2 inches thick?

We tore down at least 5000lbs of plaster and will have to tear up the floors, too. Can the blue foam insulation by used on the floor with hot water heat systems??

Thanks for any and all advice!!!