Questions regarding FLR(M)

Hello

I'm a British citizen and my non-eu husband currently has a 5 year EEA family permit valid til Dec 2019, but I'm not sure if he will be able to apply for PR anymore! So many uncertainties!

So I was thinking we should apply for a family visa from now, instead of waiting for his permit to expire.

I had some questions;

1) Can we combine our incomes to show £22,400 (incl. 1 child)? my husband is allowed to work in the UK. If so -
2) How do we calculate our income?

I am self-employed and my husband gets a salary from a LTD company that he is a director of.
Do we show 22,400 before or after tax?
And do I show profit or income of the business? For example if my sales are £2k a month, total £24k but net profit of 7,200. Is that what I show? Or can I show gross for eg. of £9,200?

3) If he applies now under the 5 year route, it will give him a 33 month visa right? Will he need to renew that or can he apply for naturalisation because he would have been lawfully resident for more than 5 years in total.

Please could someone advise.
Thanks