Questions regarding Spouse VISA Application

[Josephus]

Can someone provide an outline of the procedure for filing from USA?

I am a US Citizen

My wife is from the UK and holds dual UK/US citizenship by virtue of being married to me x 10+ years

She returned to UK in Oct, 2015; I am in process of obtaining VISA to join her as Spouse. We're good on the income requirement, legitimacy of marriage and lodging components, but a bit confused on the proper procedure for wrapping it all up

My Questions:

1) Am I required to send my US Passport in with my application to Sheffield?

2) Will I be required to travel to Wash DC to British Embassy for biometrics, or is this done regionally at a US Immigration center?

3) With the 'online' application, when asked if my spouse currently lives with me, is this a 'Yes' since we are not separated from our marriage, but only due to the fact that I had to obtain a VISA before rejoining her?

4) Will I pay for the application fees and the NHS fee at the same time online, once I submit the application?

Any assistance/advice is appreciated