If he stays out of the UK past two years then he will lose his ILR BUT he may be able to return after that as a Returning Resident. If he does, there is no need for the Life in the UK test - he will just be given his ILE immediately.
However, it is probably easiest if he naturalises now.
They can ask anything they want...though if they go too off topic a good judge will tell them to stop. They may also try to trip you up, that depends on how nice/good the HOPO is. Statistically, I find that about one in 10 is an absolute sod, most are pretty efficient and reasonably fair. Don't worr...
If you would like me to assist you, please do let me know. I agree that it is harder for those without a solid work history, and reading your other post I see you are freelance, which can make things harder. Even if you don't want me to help, please make sure that you use a firm in the UK who are so...
VFS are morons, to be ignored. They are not immigration advisors, and most of them no nothing about immigration law. What they do know is how to scare people, and how to lord it over people they don't want to help (ie everyone).