Not at all. When you see me pacing, it merely means that I am thinking. I just like to think while pacing, or pace while thinking. He's deep in thought, and I guess he just likes to think in that position. Me, I like to think while pacing.
Nothing's wrong with that, surely.
Both, and neither. Occassionally, I think in whatever broken bits of Japanese I know. But usually it's English, mixed with some Chinese. I think in whatever comes naturally, and sometimes it's English, sometimes Chinese, sometimes Spanish, and sometimes Japanese. Actually, when I'm rambling-thinking, I usually don't start thinking about how I think.