It doesnt run that hot anyway so breathing space is not so important. A 1L should work, altough i've always run that scale in a 2l.
400 ml plus about 200 of iso with the benzo will get close to 1L but a little under.
As for the column, same answer, it doesnt run so hot, its doable.
Of course neither are the 1L flask and the column perfect for that scale. I think everybody needs a 2L flask. Maybe you have one but without 3 necks. As for the column, you will need IMHO a longer one someday. If you go trhough MM nitro route it wont be sufficient. A alihin at least 400mm would be needed(i prefer the 600mm one I have)
OC