Documents to be sent

I have finished my biometric appointment. Now I need to send my application documents.

Apart from original copy of my passport and the technation letter, do I need to send any other original document? I am in USA and don’t need TB test results.

Also, in the checklist, it says that “don’t sign until you are at the appointment”, but I guess I anyway need to sign since I am sending the application by post, right?

For BRP, you must go to the center, or did you try it with the APP, which country are you applying your visa?

I am in USA.
I went to the center physically for my biometric appt. Now I am supposed to send my application in post to New York.