Yes you have to have biometrics done. The application is sent immediately after biometrics so although you submit your application online, the actual application isn't sent until after biometrics.
You submit your application. You are then prompted to sign into an account on Sopra Steria's website. At this point you choose a biometrics appointment. There are free appointments but they are normally months away (Don't worry. As long as you submit your application in time it does not matter when the biometrics appointment is). If you can wait then it is no problem. You have core centres which are standard places, enhanced which have additional benefits like checking your documents, scanning etc or premium lounge. The latter two you pay extra for, obviously.
You book your appointment and then you log into your online account to submit your documents online. You can do this yourself or pay for Sopra Steria to do it for you. Processing times i'm not sure on but we did 24 hour expedited service for £800 and we got a decision the next business day.