I am having problems combining ways where complex ways meet to form a single way. See this eg where there are several spurs to a single road/way. JOSM won’t let me combine them and I can’t work out a way in Potlatch.
It’s not possible to form complex ways. A way in OSM is a linear sequence of nodes - no junctions, T-shapes etc. allowed.
Yes, that’s the solution. Of course, only tag them the same if they actually are the same. Just because they have the same name doesn’t mean they have identical widths, surfaces or even access rights, too.