Moving to UK with Japanese spouse and child, working as contractor

[UkInJapan]

I'm a British citizen (by birth in the UK to British parents), currently living in Japan with my wife and child (for whom I'm in the process of applying for a British passport).

At this point we're not planning to move to the UK, but I'm trying to get a handle on what's involved for strategic contingency planning should the need arise, particularly regarding income and savings as it's not clear from reading various sources what applies to our situation.

- Is it possible to apply for a visa for my wife while we are living in Japan, then work out details for a move to the UK when the visa is approved? Or would I have to move to the UK and establish myself there first?

- I have been working for the last few years as a contractor for a UK-based Ltd. company (in which I hold a small amount of shares), and could continue to work for that company in the UK either as a contractor or employee; but as long as I'm in Japan I won't have any payslips etc, all I have are regular printed statements from my bank (in Japanese and English) stating how much has been remitted to my account (well over the minimum income threshold), I could also provide tax statements, and possibly get my accountant to produce some sort of evidence of income; would that cause any issues?

- I also have cash savings well over the minimum threshold, do they have to be in a UK bank account?

- Would my wife have to provide any proof of savings/income (she currently doesn't work)?

- I haven't lived in the UK since I left school in the 1990s, and beyond a single bank account and a National Insurance number which is probably associated with a few meagre payments from a couple of part-time jobs, would that cause any problems?

- Assuming all documentation is in order, is there any typical length of time for applications? (Yes, I know it's the Home Office or their outsourcers we'd be dealing with...)

For the record, my primary contingency plan involves returning to the non-UK EU country where I previously lived, where I know how the system works, but that may not be a simple option for much longer.

Any pointers gratefully accepted, not looking for exact details at this point, just an idea of what's involved and if there's anything I can do now which might be useful for a future application.