Family of a settled person visa

[cyrusgod]

Hi all,
Apologies if this is in the wrong section. Would appreciate any input on a couple of questions.
Background
About to apply for a visa for my wife. I am a British citizen living in Japan and she is Peruvian living here. We have two children (8mths and 1year 8mths, both UK passport holders) and intend to return to the UK later this year. I have a job earning around £22k in Japan and have a job lined up for around that amount so financial requirements are fine.

Questions
1 - What evidence will the company offering me UK employment need to provide (apart from a written job offer, of course!) and should they expect to need to provide accounts to UK immigration?

2 - My wife has a teenage daughter from a previous marriage who is not living with us now and will not be coming to the UK at this time. She may however want to come sometime in 2017 for study. Do I need to include her on my application and how should she be listed? I would prefer to stay at the £18.6k requirement and not be put in the £22.4k for someone that will not be coming with us, however, I do not want to damage her future chances of getting a study visa by not mentioning her now if I should.

I would appreciate any thoughts on these points and if anyone has had a similar situation.
Thanks in advance,
Ian