Ask HN: What is the role of an advisor in startup?

I was asked by an early stage startup to advise them on certain technical aspects due to my industry experience and network. Since, I never have taken such role formally, just wanted to set clear goals for myself prior to accepting to advise.

1. What is expected from startup advisor in terms of actual work and hours?

2. Does non-board member advisor have any legal implications / liabilities? I wont have any pay but part of equity, does that change anything?

3. What are advisor's boundary, are they suppose to advise and then let founders take it or leave it? or should they consider themselves as one of the employees?

4. Who would be an ideal advisor for your startup?

*edited for formatting.