면서

While doing (often trailing off)

Says two things happen at the same time, and in these lines it usually ends the sentence and lets the rest go unsaid: while you're doing it now?, while looking at Gwangalli..., wishing you all a long and healthy life.... It also introduces what somebody was thinking or saying at the time — one line has the speaker going, oh, there are other painters besides Van Gogh. Both halves have to share a subject; 으며 is the written-leaning equivalent.