Duane Ausherman has a really neat website. He knows how to "work" Google so all you have to do is Google "BMW motorcycle xxxxxxxx" filling in with the topic of the day. Most likely his website will be near or at the top.
In this case, I searched for "bmw motorcycle frame alignment check" and got this result:
http://w6rec.com/duane/bmw/frame/index.htm
It gets more and more relevant as you get further down, but read the whole page.
Unfortunately that test is only good with the bike assembled....
To check a stripped frame for straightness will probably require a frame jig, or table, made for this purpose. You will have to wait for more knowledgeable to chime in on this point.
Paint or powder coat - your choice I guess. The differences have been discussed here before, I think, but I forget who won.
It probably mostly depends on where you live and what kind of painters you have available. Some do both, and might be able to advise you, as well.
A '78 R65? Is that a first-year European model or the build date? (Mine was a first year N.A.'79 built in 11/78)
