Is a signature personal information

Answer 1

This is the approach taken by the province of Ontario, Canada under FOI:

In cases where the signature is contained on records created in a professional or official government context, it is generally not “about the individual” in a personal sense, and would not normally fall within the scope of the definition. (See, for example, Order P-773, which dealt with the identities of job competition interviewers, and Order P-194 where handwritten comments from trainers were found not to qualify as their personal information.)
In situations where identity is an issue, handwriting style has been found to qualify as personal information. (See, for example, Order P-940, which found that even when personal identifiers of candidates in a job competition were severed, their handwriting could identify them, thereby bringing the records within the scope of the definition of personal information). Order M-585 involved both handwritten and typewritten versions of a by-law complaint

For full decision: http://www.ipc.on.ca/images/Findings/Attached_PDF/MO-1194.pdf.