Ancestry Visa and Spouse Visa

I'm applying for UK citizenship as a Canadian citizen with UK Ancestry.

I think I fill out form VAF2 and the fee is £215

The ukborder website just sent me an email to say that my husband also fills out the same form and it costs the same fee. I'm hoping that is correct.

My questions are:

a) what's a reasonable amount of savings to show that I can support us?

b) we are both self-employed, would it be beneficial or required for one or both of us to search for employment instead?

c) we have a sublet for 6 months however it is a house with 2 other adults living in it. I keep reading about the living alone requirement and am nervouse that this temporary situation will result in a denial of his application.

d) is there anything else I should be aware of? any advice?