Questions to have up my sleeve for second interview!

I'm currently on mat leave - daughter is 3 months old. I went into work for a KIT day a couple of weeks ago, and there was an email in my inbox from another firm looking for a 'strategic recruit'.

I'm not looking for another job, but got in touch with them for more info. Met them on Friday for a coffee and discussion about what they're looking for and how the firm is developing. Got on really well, lots of general chat, and they effectively said that they appreciate I'm on mat leave and won't want to make any quick decisions anyway, but let's keep talking.

I've been asked to meet the Managing Partner and another Partner for lunch on Tuesday - so again, a discussion rather than an interview per se, but more formal than the first meeting. I'm not sure whether I want to move, but no harm in keeping my options open.

I feel like my brain has turned to porridge whilst on leave, so any suggestions for things I should ask about or discuss at this second meeting would be great! Plus, it's a bit of a strange situation where I've not actually applied for a job...