So taking your points one by one
If it’s external candidate then no contract has been yet been signed and so no- not their intellectual property - partly why when interviewing you should NEVER come up with solutions to company problems and issues. It is not unheard of for companies to ask candidates to do this, take the ideas and appointment no one! never ever give specific solutions or ideas if not an internal candidate, in an interview. If they like your ideas that much make them pay for it.
but if you’ve signed employment contract, that specifies intellectual property- then she is obligated to share all her ideas. Doesn’t make any difference if not in her job description. Most of us do work not in job description or where were not ordered directly to do it - we don’t get paid extra to do that, at certain levels of organisation it’s sort of expected you’ll go above and beyond and do what needs doing, regardless of job description and certainly not expecting your manager to tell you exactly what to do- it’s called initiative and making the most of opportunity. She may have chosen to do it, but it’s her employer who has provided that opportunity to “further” herself, to hers and companies benefit. doesn’t matter a jot if she did in her own time, if she wasn’t employed by them she’d not be doing it. It was for her work she did it,
if she took her knowledge and experience to another company (interview or subsequent employment) and directly lifted process, policies or ideas she’d had in previous companies she’d be liable to be sued by old company. Our contacts expressly had clause to say we could share nothing of our policies, process etc to another employer. We were banned from removing documents electronically or e copy onto personal devices, at any time - disciplinary action.
Some companies used to have contracts banning people for applying and working with competitors for 5 years once they left them- not sure if that’s legal still, but shows how seriously companies take this.
we also had clear policies for interviewing candidates over what we could and coudnt ask. Remember you interview candidates on what their potential is based on past records. Candidates can tell you a lot about past behaviour and achievements without going into fine details. We’d have taken a dim view frankly of someone tells by us stuff about our competitors intellectual property
re novel example- I had a team member who was developing a cook book (very nice samples bought in for team to try 😊). She was not allowed to work on it on company properties, or use company resources- she don’t ask , it would have been flipping obvious to her- why should she? As much as anything it would be issue in terms of her getting a full lunch break and having rest and relax time - she needed eye down time due to working at a screen quite long enough. But let’s suppose she had 2 hour lunch break, was able to bring in home device - the question becomes is what she doing related to business she’s employed in - does she work in publishing? PR? Is the novel likely to include people or places or incidents related to her work? that could still land her in issues. But if there is no connection, no potential conflicts of interest, no competitive threats, and no intellectual property transfer, then it’d probably be fine. She could certainly go off site during lunch and write away- provided it was nothing to do with her line of business. Also note, that if she gets published she may break a clause in her contract forbidding ANY other paid work whilst she’s employed.
it may sound wooly to you. It isn’t. It is simple contractual law. It’ll be clearly laid out in your contract .
If it isn’t in your contract then that’s fine, share away. But you do potentially run a risk of pissing them off, and being reprimanded or being perused through courts anyway if it gives next company a competitive advantage.
as my old company used to say “we are our people”. People provide the intellect that machines can’t replicate even with all the AI. there is now. That’s what makes them successful, or not. They are rightly extremely possessive about it.