[M.R.]

Yes you can be a nationalist and a socialdemocrat or communist, but does it make sense?

As for nationalist-liberal connection, here even in the 19th century there was no such connection, I don't know about the other countries though. Anyway as nationalism I understand modern (ethnic) nationalism we have today and doesn't have much to do with 19th century romanticism. Of course every nation has different nationalism and every nation's nationalism has different history, different heroes etc.