1. The structure of this sentence is:
> A...B...
> "On one hand A, on the other hand B" "A, while B"
The here is used to enumerate two things (in contrast). Particle usually co-occurs with this . Some examples:
> **** **** ****
> **** **** ****
> 100 **** **** 5 ****
So you can parse your sentence this way:
> A **** B ****
> "A[Kazuo may look absentminded], while on the other hand B[there are times when he has creepiness (where what he's thinking is unclear)]."
is a relative clause that modifies the noun .
Related: <
2. Right.
3. Purely grammatically speaking, the subject for is , and the subject for is . (The in here is the spontaneous auxiliary () . eg. In , the subject is .)
If you ask what the subject is for the English "feel creepy" and "don't know what Kazuo's thinking", then I think you could say it's Kazuko, or generic "you" seen from her standpoint.