I was in same boat last year. I did use paper though, and included both of my parents in one application. You need to pay biometric fee for each of your parents or applicant.

You can calculate the cost using this page https://www.uscis.gov/feecalculator

Regarding timeline, last year it took way long than I anticipated. They took one month to get the appointment letter for the fingerprinting, and almost 8 months for RFE. My Parents appeared for the biometrics, but by the time I got the RFE letter, they were already in Nepal. So, I had to reply the RFE stating that they have already left the country and no action is needed. They did send me the letter saying that their VISA was extended till the date they left US.

RFE regarding some documentation to show that they will return to Nepal on time.

Hope this helps.